Abstract:
An electrostatic precipitator for an air purifier includes a first spiral strip having a continuous conductive electrode, a second spiral strip having a continuous conductive electrode and nested with the first strip, a plurality of combs. Each comb extends from an outer periphery of the precipitator to an intermediate region between the outer periphery and a center of the precipitator.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. application Ser. No. 13/605,036 filed Sep. 6, 2012, which, in turn, claims the benefit of U.S. provisional application Ser. No. 61/532,740 filed Sep. 9, 2011, the disclosures of which are hereby incorporated in their entirety by reference herein. 
     
    
     TECHNICAL FIELD 
       [0002]    Various embodiments relate to an electrostatic air purifier. 
       BACKGROUND 
       [0003]    Indoor air quality may affect individuals including those with asthma, allergies, and other health concerns. Air contains particulate matter such as dust, pollen, soot, and the like, which may be on the order of microns or smaller. By removing the particulate matter, or particles, from the air, indoor air quality may be improved. A portable air purifier removes particulate matter from an airstream and may be used in residential, office, and other environments. The purifier may be moved from room to room, or area to area, as needed. 
       SUMMARY 
       [0004]    In an embodiment, an air purifier is provided with a frame, a fan unit supported by the frame, and an electrostatic precipitator. The electrostatic precipitator has a first strip with first and second opposing surfaces and first and second opposing edges. A first continuous conductive electrode layer extends along a portion of one of the first and second surfaces and directly adjacent to one of the first and second edges of the first strip. The electrostatic precipitator also has a second strip with first and second opposing surfaces and first and second opposing edges. A second continuous conductive electrode layer extends along one of the first and second surfaces and directly adjacent to one of the first and second edges of the second strip. The first and second strips are nested with one another. The one of the first and second edges of the first strip is opposed to the one of the first and second edges of the second strip. 
         [0005]    In another embodiment, an electrostatic precipitator for an air purifier is provided with a first spiral strip having a continuous conductive electrode, a second spiral strip having a continuous conductive electrode and nested with the first strip, and a plurality of combs. Each comb extends from an outer periphery of the precipitator to an intermediate region between the outer periphery and a center of the precipitator. 
         [0006]    In yet another embodiment, an air purifier is provided with a frame, an electrostatic precipitator supported by the frame, and a fan unit supported by the frame and positioned downstream of the electrostatic precipitator, the fan unit configured to flow air through the air purifier. The electrostatic precipitator is configured to provide electrostatic forces to remove particles from air flowing through the air purifier. The electrostatic precipitator has a first strip with a continuous conductive electrode layer along a surface of the strip and directly adjacent to an edge of the strip. The electrostatic precipitator has a second strip nested with the first strip. The second strip has a continuous conductive electrode layer along a surface of the strip and directly adjacent to an edge of the strip. The edge of the second strip is opposed to the edge of the first strip. The electrostatic precipitator also has a plurality of combs. Each comb has a support bar and teeth configured to separate adjacent strips. 
         [0007]    Various embodiments of the present disclosure have associated non-limiting advantages. For example, the combs provide for mechanical separation between electrostatic layers in the electrostatic precipitator. The combs also provide for fixed spacing between the layers of the electrostatic precipitator, which in turn may provide for improved collection of particles with more uniform electrical forces on air flowing between the layers and through the precipitator. The combs provide for consistent and precise spacing between the strips. The fixed spacing may also provide more uniform air flow through the precipitator and reduce turbulence. Also, the combs may provide for ease of manufacture as the teeth may be inserted between the layers, opposed to an adhesive method where the layers need to be appropriately spaced and kept in that position while the adhesive is applied and sets. The conductive ink being on opposed edges of adjacent layers may provide for increased distance between the electrical fields generated by the conductive ink, and improved control over the electrical fields and reduced interference between the fields generated by the conductive ink on the two layers. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a front perspective view of an air purifier according to an embodiment; 
           [0009]      FIG. 2  is a rear perspective view of the air purifier of  FIG. 1 ; 
           [0010]      FIG. 3  is a top perspective view of the air purifier of  FIG. 1 ; 
           [0011]      FIG. 4  is an exploded view of the air purifier of  FIG. 1 ; 
           [0012]      FIG. 5  is a perspective view of an electrostatic precipitator according to an embodiment; 
           [0013]      FIG. 6  is a perspective view of an upper filter core for use with the electrostatic precipitator of  FIG. 5 ; 
           [0014]      FIG. 7  is a perspective view of a lower filter core for use with the electrostatic precipitator of  FIG. 5 ; 
           [0015]      FIG. 8  is a schematic of a pair of electrostatic precipitator layers; 
           [0016]      FIG. 9  is an exploded view of the electrostatic precipitator of  FIG. 5 ; 
           [0017]      FIG. 10  is a cross-sectional perspective view of the electrostatic precipitator of  FIG. 5 ; 
           [0018]      FIG. 11  is another cross-sectional perspective view of the electrostatic precipitator of  FIG. 5 ; 
           [0019]      FIG. 12  is a side view of a comb for use with the electrostatic precipitator of  FIG. 5 ; 
           [0020]      FIG. 13  is a bottom view of the comb of  FIG. 12 ; 
           [0021]      FIG. 14  is an end view of the comb of  FIG. 12 ; 
           [0022]      FIG. 15  is a side view of another comb for use with the electrostatic precipitator of  FIG. 5 ; 
           [0023]      FIG. 16  is a bottom view of the comb of  FIG. 15 ; and 
           [0024]      FIG. 17  is an end view of the comb of  FIG. 15 . 
       
    
    
     DETAILED DESCRIPTION 
       [0025]    As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention. 
         [0026]      FIGS. 1 and 2  illustrate an air purifier  20  capable of electrostatic precipitation of particulate matter, or particles, from the ambient air. The air purifier  20  has a cover  22  or enclosure which may contain a front portion  24  and a back portion  26 . The cover  22  may contain apertures  28  such as holes, perforations, or slots in the front cover  24  and back cover  26  to allow air to flow through the unit  20 , and be purified by an electrostatic precipitator contained within the unit  20 . A base  30  supports the unit  20  on an underlying surface, such as a tabletop, floor, or the like. Other bases are also contemplated for use with the air purifier  20 . The air purifier  20  has an electrical power cord  32  which allows the unit  20  to be plugged into a wall electrical outlet to supply the purifier with electricity. Alternatively, the unit  20  may contain a compartment for batteries or an alternate power source to provide the unit  20  with stand-alone power. 
         [0027]      FIG. 3  illustrates a top perspective view of the air purifier showing a user interface panel  33 . The user interface panel  33  provides one or more inputs or controls for a user to control the air purifier  20 . For example, the air purifier may be equipped with a power button, a fan speed control button or dial, a timer such that the air purifier turns off after a designated time such as one hour, two hours, four hours, etc. The user interface may also contain lights, such as light emitting diodes, that act to provide information to the user, such as for changing a filter component of the purifier  20 . 
         [0028]      FIG. 4  is an exploded view of the air purifier  20 . The air flow  34  is shown as flowing from the ambient environment, through the unit  20  entering at the back cover  26  and exiting at the front cover  24  out of the unit  20  as purified air. Although the present disclosure describes the air flow as from the back cover  26  to the front cover  24 , the direction is not meant to be limiting. For example, the purifier  20  may also be configured such that the air flows in the opposing direction from the front cover  24  to the back cover  26 . 
         [0029]    The air flow  34  enters through perforations  28  in the back cover  26 . The air then proceeds to flow through a pre-filter  36 . The pre-filter  36  removes large particles and matter from the air stream  34  before the air flows through the electrostatic precipitator  38 . The pre-filter  36  may be made from a paper, mesh material, screen, or other material as is known in the art to remove larger particles or other matter. 
         [0030]    The air then flows from the pre-filter  36  and into the electrostatic precipitator  38 , which is in electrical communication with the power cord  32 . The electrostatic precipitator  38  creates electrostatic forces within the precipitator  38  such that particles are removed from the air flow  34  and deposited onto the surface of the precipitator  38 . The particles may have been charged or partially charged by a corona discharge or electrical field created by metal ring  50  and electrode or ionizer  55 . The electrostatic precipitator  38  removes at least a portion of particulate matter contained in the air stream  34 . In one example, the electrostatic precipitator  38 , which is located downstream of the pre-filter  36 , provides electrostatic forces to attract particles on the order of down to 0.01 microns or down to 0.1 microns. 
         [0031]    A frame  40  is connected to the base  30  and acts to support the various components of the unit  20 . The frame  40  has a support member  42  surrounded by a recessed area  44 . The support member  42  and recessed area  44  are sized to receive and support the electrostatic precipitator  38  and the pre-filter  36 . The electrostatic precipitator  38  has an aperture  46  which fits over and is supported by the support member  42 . The electrostatic precipitator  38  may have clips on an inner surface of the aperture  46  that align with corresponding clips on the support member  42  to secure or retain the precipitator  38  to the support member  42 . The clips on the precipitator  38  and the support member  42  may also act to provide electricity to the conductive ink electrodes  64 ,  68 . The pre-filter  36  also has an aperture  48  which fits over and is supported by the support member  42 . 
         [0032]    The back cover  28  attaches to the frame  40  to retain the electrostatic precipitator  38  and pre-filter  36  within the recessed area  44  of the frame  40 . A metal conductive ring  50  may be provided on the back cover  26  and be electrically connected or in electrical communication with an electrical ground or one of the power supplies  52 ,  54 . The back cover  26  is connected to the frame  40  using fasteners such as clips, screws, or other fasteners as are known in the art. On some embodiments, the back cover  26  is designed to be removable by a user to replace or clean the pre-filter or electrostatic precipitator as necessary. 
         [0033]    A power supply  52  and a high voltage power supply  54  are connected to one of the frame  40  and the base  30 . Electricity flowing through the power cord  32  enters the main power supply  52 , which is in electrical communication with the high voltage power supply  54 . The high voltage power supply  54  increases the voltage for use with the electrostatic precipitator  38 . Electrical connections on the support member  42  transfer electricity from the high voltage power supply  54  to the electrostatic precipitator  38  to create the electrostatic forces. Of course, other locations for electrical connections between the high voltage power supply  54  and the electrostatic precipitator  38  are also contemplated. 
         [0034]    An ionizer brush  55  or electrode is connected to the support member  42  and ionizes ambient air. The ionizer brush  55  may extend through an aperture in the cover  26  such that it extends outside the unit  20 . The ionizer brush  55  may introduce ions into the ambient air or into the air stream  34  to offset ozone or NOx created by the electrostatic precipitator  38 . The ionizer brush  55  is connected to the power supply  52  or the high voltage power supply  54 . In some embodiments, the ring  50  acts as a ground for the ionizer brush  55  to prevent corona discharge and arcing and also to prevent ozone formation. The ring  50  and ionizer brush  55  may additionally act to charge or partially charge the particles before they reach the precipitator. 
         [0035]    A series of apertures, perforations, or holes  56  are provided within the recess area  44  of the frame  40 . The apertures  56  allow airflow from the electrostatic precipitator  38  and through the frame  40 . The air is drawn through the unit  20  by a fan unit  58 . The fan unit  58  is shown as having four fans arranged in an array; however, any number of fans are contemplated for use with the unit  20 . Power to the fan unit  58  is provided by the power supply  52 . The fan unit  58  is attached to the frame  40  using fasteners as is known in the art. 
         [0036]    Trim  60  may be provided with the unit  20  to connect the frame  40  to the front cover  24  and provide spacing for the fans  58 . The front cover  24  connects to the trim  60 , or alternatively, directly to the frame  40  using fasteners such as clips, screws, or other fasteners as are known in the art. 
         [0037]    The front cover  24  has a series of apertures  28  which permit the air stream  34  to exit the unit  20  and provide purified or cleaned air to the ambient environment. The apertures  28  may be patterned such that they are in line with the fans in the fan unit  58 , as is shown in  FIG. 4 . Alternatively, the apertures  28  may extend over a majority of the front cover  24 . 
         [0038]    As is shown in  FIG. 4 , the air flow goes through the pre-filter  36  and the electrostatic precipitator  38  before flowing through the fan unit  58  and out of the unit  20 . Therefore, the filtering units  36 ,  38  are located upstream of the fan unit  58 . 
         [0039]    The electrostatic precipitator  38  is shown in  FIG. 5 . The electrostatic precipitator  38  is made from two concentric nested spiral layers or strips. A section of the two layers is shown in  FIG. 8 . The layers or strips may be made from paper, cloth, or other non-conductive material. In one embodiment, the layers include paper fiber, wood pulp, and CaCO3. The first layer  62  has a stripe or layer of conductive ink  64  located along and directly adjacent to an edge of the layer  62  and on one side of the layer  62 . The second layer  66  has another stripe of conductive ink  68 . The ink  68  is located along and directly adjacent to the edge of the layer  66  and on one side or one surface of the layer  66 . The ink stripes  64  and  68  are located on opposing edges of the layers  62 ,  66 , respectively. The conductive ink stripes  64 ,  68  act as electrodes and create an electrical field to charge or attract particles in the nearby air flowing past the layers. 
         [0040]    In one embodiment, described with respect to  FIG. 8 , each layer  62 ,  66  has a pair of sides or surfaces and a pair of edges. Each side of a layer  62 ,  66  is approximately 25 mm. Each edge is approximately 0.35-0.50 mm based on whether the measurement is taken before or after compression of the layer. The ink  64 ,  68  is positioned on a side of the respective layer  62 ,  66  and directly adjacent to an edge of a layer. The ink is approximately 3 mm in width and 0.02 mm in thickness on the layer. The dimensions of the layers  62 ,  66  and the ink  64 ,  68  provide for spacing between the two ink stripes  64 ,  68  of more than five times, or even more than six times the width of an ink stripe  64 ,  68  between adjacent layers. 
         [0041]    Referring back to  FIG. 5 , the precipitator unit  38  is made from the first and second layers  64 ,  66  wound into a concentric nested spiral  70 . The layers  64 ,  66  are wound such that every other layer within the spiral  70  has the conductive ink on the same edge or side of the spiral  70 . The ink stripe runs continuously along the entire length of each layer and is directly adjacent to the edge of the layer. In one embodiment, each layer is approximately 20 meters in length, 25 millimeters in width, and 0.35 millimeters in thickness. In some embodiments, the conductive electrode is an ink stripe which is 3 millimeters wide and 0.2 millimeters in thickness. The ink is made from a conductive material applied on one side or one surface of the layer. The other side or surface of the layer may be uncoated with any conductive ink, and therefore be generally insulative. The ink may be painted, sprayed, or otherwise applied to the layer. Some embodiments have a moisture proof layer or coating  72  applied over the layer and the ink. The moisture proof layer  72  may be a 45 micrometer thick polyethylene (PE) coating. The coating  72  serves to protect the paper and the ink from humidity in the air stream  34 . 
         [0042]    In one example, the moisture proof coating  72  is at least 41 micrometers thick, which allows for electrostatic forces for particle precipitation and preventing humidity from reaching the layer or the ink. In another example, the moisture proof coating  72  is at least 20 micrometers thick. 
         [0043]    The ink strips  64  and  68  being on opposing edges of the layer provide enlarged spacing between the conductive strips which additionally spaces the electrical forces and fields provide by the conductive ink. This may provide increased precipitation of any particles in the ambient air, and reduce the possibility of electrical interference between the conductive inks  64 ,  68 . Therefore the ink is directly adjacent to and in contact with the edge of the layer  62 ,  66 . 
         [0044]    The spiral  70  is positioned and retained to the precipitator  38  using an upper filter core  74  as shown in  FIG. 6 , a lower filter core  76 , as shown in  FIG. 7 , and several long combs  78  and short combs  80 , as shown in  FIG. 5 . 
         [0045]    The upper filter core  74  is shown in  FIG. 6  with a generally cylindrical structure  82 . In one embodiment, the upper filter core  74  also has a pair of flange members  84  extending from the cylindrical structure  82 . In other embodiments, the flange members  84  are not present, as shown in  FIG. 9 . A series of mounting points  86  are formed into the cylindrical member  82  to attach the combs  78 . The flange members  84  act to align the layers in the spiral  70 . 
         [0046]    The lower filter core  76 , as shown in  FIG. 7 , has a generally cylindrical structure  88 . In one embodiment, a pair of flange members  90  extend from the generally cylindrical structure  88  and serve to align the layers in the spiral. In other embodiments, the flange members  90  are not present in the lower filter core, as shown in  FIG. 9 . The lower filter core  76  has a series of mounting points  92  for combs  78 . 
         [0047]    The lower filter core  76  additionally has a pair of electrical contacts  94  for transmitting electricity to the conductive ink in the spiral  70 . Of course, the electrical contacts  94  may be located on the upper filter core  74  or alternatively one metal contact may be located on the upper filter core and the other metal contact located on the lower filter core  76 . The pair of electrical contacts  94  includes a positive contact and a negative or ground contact. One of the electrical contacts  94  transmits electricity between the high voltage power supply  54  and the first layer  64 . The other electrical contact  94  transmits electricity between the high voltage power supply  54  and the second layer  66 . This creates an opposing electrical charge on the two stripes of conductive ink  64 ,  68 . The electrical contacts  94  may be the clips used to retain the precipitator to the support member  42  and cooperate with corresponding clips on the support member  42  to transmit electricity. 
         [0048]    For example, the upstream stripe of ink is charged, which charges any particles in the air stream  34 . The downstream stripe of ink is grounded, attracts the charged particles by exerting an electrostatic force on them, and causes the particles to precipitate or deposit onto the downstream stripe of ink. The particles may have been previously charged by the ionizer  55  upstream of the precipitator  38 . 
         [0049]    The upper and lower filter cores  74 ,  76  may snap, or clip, or otherwise attach to one another, thereby retaining the spiral  70 . A handle  96  attaches to the upper filter core  74  to allow for handling of the precipitator  38 . The handle  96 , the upper filter core  74 , and the lower filter core  76  may be made from a non-conductive material, such as a plastic, to prevent electrical shocks to a user during handling of the precipitator  38 , and for ease of manufacturing. 
         [0050]    An exploded view of the precipitator  38  is shown in  FIG. 9 . The first layer  62  and second layer  66  are wound into a spiral shape together such that they are nested and concentric. The electrical contacts  94  provide electricity to the conductive ink on the layers. 
         [0051]    The first series of combs  78  and second series of combs  80  act to separate the layers  62 ,  66  from one another and provide appropriate spacing between the layers  62 ,  66 . The upper filter core  74  and lower filter core  76  act as a retainer for the precipitator unit  38  and provide mounting points for the combs  78  and the electrical contacts  94 . 
         [0052]      FIG. 10  illustrates a cross sectional perspective view of the precipitator filter  38  depicting the cross section of the small combs  80 . The small combs  80  are used for the wider diameter portion of the precipitator filter  38 , such that a layer is not unsupported or unseparated by a comb for an extended length. A pair of combs  80  is provided on either side of the spiral  70  and across from one another. 
         [0053]      FIG. 11  illustrates a cross sectional perspective view of the precipitator filter  38  showing a cross section of the combs  78 . The combs  78  extend the width of the radial direction of the spiral  70 . A pair of combs  78  is provided such that there is a comb  78  on either side of the spiral  70  across from one another. A pair of combs  78  is located at multiple positions around the precipitator unit  38 , and directly opposed to one another. The combs  78  act to provide mechanical spacing and separation between the layers  62 ,  66  such that they do not come into contact with one another to cause an electrical short, and such that the spacing is appropriate to create electrostatic forces which provide deposition of the particles in the air stream  34 . 
         [0054]    The combs  78  are shown in  FIGS. 12-14 . The comb  78  has a support bar  98  that extends the length of the comb  78 . Extending from the support bar  98  is a series of teeth  100 . As shown in  FIGS. 11 and 13 , the teeth  100  are generally triangular and are tapered towards the free ends of the teeth  100 . Of course, other shapes for the teeth  100  are also contemplated. An aperture  102  cooperates with the mounting points  86  of the upper filter core  74  or the mounting points  92  of the lower filter core  76  to attach the combs  78 . 
         [0055]    In one embodiment, the total length of the comb is 108 millimeters, the length with teeth is 100 millimeters, the width of the comb is 6 millimeters, and the length of the teeth (or thickness of the comb) is 8 millimeters. Of course, other sizes are envisioned for use with the unit  20 . 
         [0056]    The combs  80  are illustrated in  FIGS. 15-17 . The teeth  104  extend the length of the comb  80  and are supported by a support bar  106 . In one embodiment, the length of the comb  80  is 17.5 millimeters, the width of the comb is 6 millimeters, and the length of the tooth (Original) thickness of the comb) is 8 millimeters. Of course, other dimensions for the comb  80  are envisioned for use with the unit  20 . The teeth on the comb may be sized such that they extend to an intermediate region of a layer, and are less than the width of the layer. 
         [0057]    Various embodiments of the present disclosure have associated non-limiting advantages. For example, the combs provide for mechanical separation between electrostatic layers in the electrostatic precipitator. The combs also provide for fixed spacing between the layers of the electrostatic precipitator, which in turn may provide for improved collection of particles with more uniform electrical forces on air flowing between the layers and through the precipitator. The combs provide for consistent and precise spacing between the strips. The fixed spacing may also provide more uniform air flow through the precipitator and reduce turbulence. Also, the combs may provide for ease of manufacture as the teeth may be inserted between the layers, opposed to an adhesive method where the layers need to be appropriately spaced and kept in that position while the adhesive is applied and sets. The conductive ink being on opposed edges of adjacent layers may provide for increased distance between the electrical fields generated by the conductive ink, and improved control over the electrical fields and reduced interference between the fields generated by the conductive ink on the two layers. 
         [0058]    While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.