Abstract:
To provide a room with a soft lighting effect and to enhance the appearance of an exposed air duct, a fabric duct is provided with a light-transmitting fabric wall that is illuminated, such that light from inside the duct travels outward into the room. In some embodiments, various colored lights and/or blinking patterns create special lighting effects that simulate the temperature or flow rate of the air being conveyed through the duct. In some cases, ultraviolet light is used to help kill microorganisms inside the air duct.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The subject invention generally pertains to air ducts and more specifically to an illuminated fabric air duct.  
           [0003]    2. Description of Related Art  
           [0004]    Many HVAC systems (heating ventilating and air conditioning systems) include a network of air ducts with several discharge registers that distribute forced air to various rooms or areas within a building. Conventional air ducts are made of sheet metal, which is functional, but often considered not very attractive. But their appearance is usually not that important, as ductwork is often conveniently installed where they are out of sight, such as hidden above a ceiling or below a floor of the area being ventilated.  
           [0005]    However, some buildings, such as warehouses and factories, do not have a convenient, out of sight location to install metal ductwork. In such cases, the ductwork is often installed just below the ceiling where it is in clear view. Moreover, if the ductwork conveys cool air, condensation may form on the exterior metal walls of the ducts, which may then drip onto the inventory or personnel below. The consequences of the dripping can range anywhere from a minor irritation to a dangerously slippery floor for the personnel, or complete destruction of the products it may drip on (especially in food-processing facilities).  
           [0006]    Sometimes, temperature differentials between the ducts and the air being conveyed creates condensation on the interior of the ducts. The presence of condensed moisture on the duct&#39;s interior may form mold or bacteria that the duct then passes onto the room or other areas being supplied with the conditioned air.  
           [0007]    In some applications, the rooms or areas being served by the ductwork require a more even distribution of air than what can be achieved with several spaced-apart discharge registers. Metal ducts with localized discharge registers have been known to create uncomfortable drafts and unbalanced localized heating or cooling within the discharge registers. Metal ducts with localized discharge registers have been known to create uncomfortable drafts and unbalanced localized heating or cooling within the building. In many food-processing facilities, where the target temperature is 42 degrees Fahrenheit, a cold draft can be especially uncomfortable and possibly unhealthy.  
           [0008]    Consequently, for the reasons just mentioned, air ducts made of fabric are often preferred over those made of sheet metal. Fabric ducts typically have a flexible fabric wall that is porous and/or includes additional holes along its length for evenly dispersing air from within the duct into the areas being conditioned or ventilated. The fabric&#39;s ability to “breathe” appears to minimize condensate accumulation on both the interior and exterior of the duct. An example of such a duct is a DUCTSOX by the Frommelt Safety Products Corporation of Milwaukee, Wis.  
           [0009]    Since fabric ducts disperse air generally along its entire length, fabric ducts are usually installed such that they are fully exposed to the area they serve. Fabric ducts are often suspended from a horizontal cable or track mounted just below the ceiling of the building. Thus, they are usually clearly visible, which makes their appearance generally more important than if they were hidden. Although many prefer the appearance of fabric ducts over those made of sheet metal, there may always be a desire to further enhance their appearance.  
         SUMMARY OF THE INVENTION  
         [0010]    A fabric air duct is provided with a light-transmitting fabric wall that is illuminated, such that light travels outward from inside the duct. Such a fabric duct may exhibit an enhanced appearance over existing ducts, and has added functionality.  
           [0011]    In some embodiments, a fabric air duct and a light source are suspended underneath a ceiling using the same hangers.  
           [0012]    In some embodiments, the light-transmitting fabric wall is translucent to broadly disperse light into a room.  
           [0013]    In some embodiments, the interior of a fabric air duct is illuminated with ultraviolet radiation to kill or inhibit the growth of microorganisms, such as mold, fungus, or bacteria.  
           [0014]    In some embodiments, the interior of a fabric air duct is illuminated with a light that changes with a changing condition of the air being conveyed through the duct, wherein the changing condition of the air is temperature, pressure or rate of airflow.  
           [0015]    In some embodiments, the interior of a fabric air duct is illuminated with blinking lights to create a twinkling or moving-light effect.  
           [0016]    Alternatively, light may not pass through the duct, but the duct and indirect lighting may be commonly mounted. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    [0017]FIG. 1 is a front view of one embodiment of an illuminated fabric air duct.  
         [0018]    [0018]FIG. 2 is a cross-sectional end view taken along line  2 - 2  of FIG. 1.  
         [0019]    [0019]FIG. 3 is similar to FIG. 2, but with the air duct inflated.  
         [0020]    [0020]FIG. 4 is a cross-sectional end view of an inflated cylindrical fabric air duct illuminated by an adjacent light source.  
         [0021]    [0021]FIG. 5 is a front view of another embodiment of an illuminated fabric air duct.  
         [0022]    [0022]FIG. 6 is a front view with a partial cut-away of another embodiment of an illuminated fabric air duct.  
         [0023]    [0023]FIG. 7 is similar to FIG. 2 but with a light fixture directing light generally away from a fabric duct to provide indirect lighting to areas below the duct. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0024]    To disperse light as well as air into a room, an air duct assembly  10 , of FIGS.  1 - 3 , includes a light source  12  shining through a light-transmitting fabric wall  14  of a fabric air duct  16 . The term, “fabric,” refers to any pliable sheet of material that may or may not be air permeable or porous. Examples of a fabric include, but are not limited to, woven or knit cloth, flexible plastic sheeting that is not necessarily woven, plastic impregnated cloth, fiber reinforced plastic, and various combinations thereof. The term, “light-transmitting” refers to a material having the ability to pass light either through itself or through openings in the material, wherein the material may be transparent (colorless or tinted), translucent, or opaque with openings. Air duct  16  is shown with several hangers  18  suspending duct  16  from girder beams of a ceiling  20 .  
         [0025]    To provide duct  16  with the ability to convey air  22  along its length, longitudinal edges of fabric wall  14  connect to a top plate  24  to create a tubular shape, as shown in FIGS. 2 and 3. The tubular shape can be created by a variety of structures; however, in this example two channels  26  attached along the length of plate  24  couple opposite edges of plate  24  to two elongated beads  30  running lengthwise along fabric wall  14 . A lengthwise sliding fit between beads  30  and channels  26  allows fabric wall  14  to be periodically removed for cleaning and later reinstalled. An air handler  32 , such as a blower  34  disposed within a housing  36  or some other source of forced air, discharges air  22  through an interior  38  of duct  16 . A fabric end cap  40  restricts or entirely closes off a downstream end of duct  16  to help develop a positive air pressure that inflates duct  16  when blower  34  is running, as shown in FIG. 3. When blower  34  turns off, duct  16  deflates, as shown in FIG. 2.  
         [0026]    To expel pressurize air  22  from within duct  16  and disperse it into an exterior area  42  surrounding duct  16 , fabric wall  14  is air-permeable. Air-permeability of wall  14  can be provided by fabric porosity and/or by small openings distributed along the length of duct  16 .  
         [0027]    To transmit light  44  outward from within duct  16  and disperse the light into area  42 , light source  12  is mounted to project an appreciable amount of its light  44  into duct  16 . In this embodiment, light source  12  projects its light  44  through plate  24 , which illuminates an interior surface  46  of duct  16 . Plate  24  can be made of clear plastic or glass, or plate  24  could be translucent or even opaque with a central opening for the light. From the illuminated interior  38 , light  44  travels outward from duct  16  after passing through the light-transmitting fabric wall  14 . Light source  12  is schematically illustrated to encompass anything that can provide illumination. Examples of light source  12  include, but are not limited to, a fluorescent light, an incandescent light, halogen bulb, an ultraviolet light, and a lens or reflective surface that redirects light from another light source.  
         [0028]    Light source  12  can be selectively turned on and off as needed. In some cases it may be desirable to have light source  12  turn on and off automatically with the operation of blower  34 . For example, light source  12  turns off when blower  34  turns off, and turns on when blower  34  turns on, as shown in FIGS. 2 and 3, respectively. Conversely, light  12  turning on when blower  34  turns off may be useful when light source  12  is an ultraviolet light used for killing microorganisms that tend to grow in dark, stagnant environments. A combination of the two approaches could also be useful. For example, a conventional fluorescent light could be turned on and off as needed, and an additional ultraviolet light could be operated whenever blower  34  turns off.  
         [0029]    In another embodiment, shown in FIG. 4, an air duct  48  having a generally cylindrical, light-transmitting fabric wall  50  is situated adjacent a light source  52 . This tends to provide duct  48  with a “glowing” effect when most or at least 20 percent of the light emitted from light source  52  reaches duct  48 . In other words, angle  54  is at least 20 percent of the sum of angles  54 ,  56  and  58 . The glowing effect is achieved by light  60  first passing through fabric wall  50  to illuminate an interior  62  of duct  48  and then passing through fabric wall  50  again to shine outward, away from duct  48 .  
         [0030]    Air duct  48  can also be illuminated as shown in FIG. 5. Here, two light sources  64  and  66 , in the form of a conventional spot light or a flood light, shine in a direction generally parallel to the duct&#39;s length or generally parallel to the direction that air  22  flows through duct  48 . This illuminates the interior of duct  48  and thus illuminates its exterior, as well. Light  66  disposed outside of duct  48  illuminates the duct&#39;s interior by projecting its light  68  through an airflow opening  70  or closed window of an end cap  72 . Light  66  is disposed within the interior of housing  36  and/or the interior of duct  48 . Either light  64  or  66  can be used alone or with each other.  
         [0031]    In some cases, it may be desirable to have one light  64  or  66  emit red light and the other blue. The red one could be turned on when duct  48  is conveying warm air, and the blue one could turn on when duct  48  is conveying cool air. The distinction between the red and blue colors may be more apparent if the fabric of duct  48  is white or nearly white.  
         [0032]    Several openings  74  in duct  48  provide discharge airflow rates that are higher than what may be achieved by relying on fabric porosity alone. Openings  74  not only allow the use of nonporous fabric, but openings  74  also allow an opaque fabric wall to transmit light.  
         [0033]    Other special lighting effects can be achieved with a duct assembly  76  of FIG. 6. In this embodiment, a string of lights  78 , such as those often referred to as “rope lights,” “Christmas lights” or “holiday lights,” serves as the light source that illuminates the interior, and thus the exterior, of a light-transmitting fabric air duct  80 . The string of lights  78  includes a series of small bulbs  82  that can blink on and off randomly to provide a “twinkling” effect or can blink in a sequential pattern to provide a “traveling light” effect where the lights appear to be moving. If blower  34  is a dual-speed blower, lights  82  can be blinked in such a way as to create a perceived speed of movement that increases with an increase in blower speed. Light bulbs  82  can be of an assortment of different colors or be all of the same color. Lights  82  do not necessarily have to blink, but instead can be left on or off continuously, as needed.  
         [0034]    In another embodiment, an air duct assembly  10 ′ is similar to that of FIGS.  1 - 3 ; however, instead of light source  12  focusing most of its light toward duct  16 , duct assembly  10 ′ includes a light source  12 ′ that is inverted to direct most of its light  44 ′ away from duct  16 . This provides indirect lighting to areas underneath duct  16  as the light reflects off the ceiling and other surfaces. Yet, air duct assemblies  10  and  10 ′ are similar in that each includes hangers  18  that suspend both a light source and a fabric air duct from underneath a ceiling.  
         [0035]    Although the invention is described with reference to a preferred embodiment, it should be appreciated by those skilled in the art that various modifications are well within the scope of the invention. Therefore, the scope of the invention is to be determined by reference to the claims that follow.