Abstract:
The conventional fan blade is replaced by a frame over which any of a wide range of decorative fabrics or other similar materials is drawn and secured by a clamping method to form a lightweight fan blade of any surface design desired by the user. The decorative fabric replaces the heavy fan blade while still providing its function of air circulation. The same decorative fabrics or other similar materials are also used as coverings or trim for the body of the fan motor housing. The fan blade frame may take any shape suitable for causing the circulation of air as by a conventional fan blade. Elimination of the fan blade mass of conventional designs makes possible significant reductions in power consumption, and significant reductions in stress, wear, and tear on the fan&#39;s ceiling mountings.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of the filing date of U.S. provisional patent application Ser. No. 60/468,875 filed May 8, 2003. 

   FIELD OF THE INVENTION 
   This invention relates to ceiling fans, and relates more specifically to ceiling fan blades with decorative appearance and their fabrication and mounting. 
   BACKGROUND OF THE INVENTION 
   Ceiling fans provide both air circulation and decoration to the rooms in which they are mounted. Conventional ceiling fans have long blades made of wood or other rigid materials which circulate air upward or downward according to the pitch of the blades and the direction of rotation of the set of blades. There are disadvantages to these conventional fans. First, the blades are large and heavy, adding considerable weight to the fan and thereby stressing the fan&#39;s mounting in the ceiling. Often such blades are not properly matched in weight, and when the fan is turning, the weight imbalance of such unmatched blades causes the entire fan to wobble on its ceiling mounting, thereby putting additional stress on the mounting and presenting a risk of mounting failure. Mounting failure results in the falling of the fan from the ceiling. 
   Second, the weight of the blades necessitates use of a large fan motor, to drive the blades through the air at any of the desired speeds of the fan. The size of the motor dictates the amount of electrical power it consumes and the larger motors consume more power. 
   Third, the composition and mounting requirements of the blades restrict the role the fan can play in the decorative scheme of the room in which the fan is mounted. A change in decor can make the fan appear out of place in the room. Given the makeup of the fan blades, the only means of solving this problem is to paint the blades a different color, or to coat them in some manner with a decorative layer. 
   Several patents provide for decorative covering of the fan blades. U.S. Pat. No. 5,947,686, “Fan blade covers” (Keyes) teaches the use of sleeves made of cloth or other flexible, washable material to cover each fan blade, with each sleeve secured by tabs of material. U.S. Pat. No. 5,591,006 “Decorative cover for ceiling fan blade” (DeMeo, et al.) teaches the use of sleeves made of stretchable fabric which are held in position by friction caused by the tightness of fit of the fabric against the fan blade surface. U.S. Pat. No. 6,019,479 “Multi-fastening, one-piece, decorative fan blade cover and strobe light” (Barker) teaches the use of folding covers with tabs and slots for securing the covers over the fan blades. All of these approaches to changing the appearance of the fan blades add weight and bulk to the fan and blades, which are already heavy. Furthermore, none of these conventional approaches substantially changes the shape of the fan blade. 
   SUMMARY OF THE INVENTION 
   The invention replaces the conventional fan blade with a frame over which any of a wide range of decorative fabrics or other similar materials is drawn and secured by a clamping method to form a lightweight fan blade of any surface design desired by the user. The decorative fabric thus replaces the heavy fan blade while still providing its function of air circulation. The frame of the invention may take any of a number of shapes suitable for causing the circulation of air as by a conventional fan blade. The invention permits the user to apply the same decorative fabrics or other similar materials on the fan blades to coverings or trim for the body of the fan motor housing. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows the invention&#39;s fan blade frame and a piece of fabric to be used for the fan blade. 
       FIGS. 1A through 1F  show different methods of attaching the fabric to the fan blade frame to form a single face of the blade. 
       FIGS. 1G through 1L  show different methods of attaching the fabric to the fan blade frame to form both faces of the blade. 
       FIGS. 2A through 2D  show the process of fastening the fabric to the frame. 
       FIG. 3  shows the invention&#39;s fan blade frame with added cross braces. 
       FIGS. 3A through 3F  show different shapes of the invention&#39;s fan blades. 
       FIGS. 3G and 3H  show the orientation of the invention&#39;s fan blades with respect to the fan motor housing. 
       FIGS. 3I and 3J  show a top view of each of two different fans according to the invention, using the fan blades of  FIGS. 3C and 3F  respectively. 
       FIGS. 3K and 3L  show a top and bottom view respectively of the fan using the fan blade of  FIG. 3F . 
       FIGS. 4A ,  4 B, and  4 C show the process of attaching fabric to the fan motor housing. 
       FIG. 5  shows details of the strut attaching the fan blade to the drive shaft of the fan motor housing. 
       FIG. 6  is a view of an expansion ring that holds fabric against the inside wall of the blade frame. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The invention comprises a set of fan blades. Each fan blade is made by stretching fabric over a rigid frame or hoop and securing the fabric tightly to the frame, as shown in  FIGS. 1 and 2A  through  2 D. The fabric forms the operating surfaces of the fan blade. The invention&#39;s fan blade design uses a simple and quick method for putting fabric onto a fan blade, and onto the fan body or motor housing, without the use of tools or extensive procedures. 
   In the first step, shown in  FIG. 1 , a fabric  10  is laid flat, the fan blade frame  20  is then laid on top of the fabric  10  to allow the fabric  10  to be cut to the approximate size needed to be stretched across the fan blade frame  20  and anchored. The fabric  10  may be any woven or knitted natural cloth such as cotton, linen, or silk, or it may be any woven or knitted synthetic cloth such as nylon, rayon, or acetate, or it may be any uniform flexible flat substance capable of being stretched across a frame and anchored to the frame, such as treated canvas, plastic film, or leather. The fabric  10  may carry any design or pattern desired, in any desired colors. The fan blade frame  20  may be made of any solid material, such as wood, metal, or plastic, capable of supporting the weight of the stretched fabric, the tension of the stretched fabric, and the rotational and acceleration stresses of the fan&#39;s operation. 
   The invention secures the fabric  10  to the blade frame  20  using an elastic band, a spring clamp, any manually operated tensioning device, or any other means which keep the fabric  10  stretched across the blade frame  20  during operation of the fan without detracting from its appearance. See  FIGS. 1A through 1C  for the securing of fabric  10  against the blade frame  20 .  FIG. 1A  shows a cross section of the frame  20  and a groove  22  in the outward facing side of frame  20 .  FIG. 1B  shows fabric  10  being placed in groove  22 . An elastic band is then stretched to a size permitting it to be fitted into groove  22 .  FIG. 1C  shows fabric  10  tightened and secured by elastic band  30  within groove  22  of frame  20 . Part  10   a  of fabric  10  is thus stretched across frame  20 . 
   Other methods of securing the fabric  10  to the frame  20  include, but are not limited to the following embodiments. In one such embodiment, shown in cross section in  FIG. 1D , an outer hoop  25  surrounding frame  20  and fitting tightly against it is used to clamp the fabric  10  securely once it is stretched across frame  20  to the desired degree of tightness. Outer hoop  25  is concentric with frame  20  and is tightened in groove  22  over fabric  10  by means of a tensioning clasp or other conventional closure device (not shown) to close outer hoop  25  tightly around frame  20 . 
   In another embodiment, shown in  FIG. 1E , outer hoop  25  concentric with frame  20  as in  FIG. 1D  is used. Pins, screws or bolts  27  are inserted through outer hoop  25 , fabric  10 , and frame  20  to anchor fabric  10  securely once it is stretched across frame  20  to the desired degree of tightness. 
   In still another embodiment, shown in  FIG. 1F , outer hoop  25  concentric with frame  20  is used as in  FIG. 1D , but to provide added security to the fabric clamped between outer hoop  25  and frame  20 , outer hoop  25  is fabricated with teeth  28  oriented to oppose the loosening of fabric  10  while it is under tension across frame  20 . 
   In yet further embodiments, the invention&#39;s fan blades may be made with fabric  12  stretched across the top of each fan blade and fabric  10  stretched across the bottom of each fan blade, to prevent accumulations of debris in the cavity made by the frame and the bottom layer of fabric  10 .  FIG. 1G  shows the anchoring of top layer fabric  12  to frame  20  using a first outer hoop  24 .  FIG. 1H  shows the anchoring of bottom layer fabric  10  as in embodiments described earlier to frame  20  using a second outer hoop  25 . Both outer hoops are tightened in groove  22  over fabric  10  by means of a tensioning clasp or other conventional closure device (not shown) to close outer hoop  25  tightly around frame  20 . 
   In still another embodiment, shown in  FIG. 1I , first outer hoop  24  concentric with frame  20  is used to anchor top layer fabric  12  to frame  20  using pins, screws or bolts  27 .  FIG. 1J  shows second outer hoop  25  concentric with frame  20 , holding bottom layer fabric  10 . Pins, screws or bolts  27  are inserted through outer hoop  25 , fabric  10 , and frame  20  to anchor fabric  10  securely once it is stretched across frame  20  to the desired degree of tightness. 
   In still another embodiment, shown in  FIG. 1K , first outer hoop  24  concentric with frame  20  is used to anchor top layer fabric  12  to frame  20 , and second outer hoop  25  concentric with frame  20  is used to anchor bottom layer fabric  10 , but o provide added security to the fabric clamped between outer hoop  25  and frame  20 , both inner hoop  24  and outer hoop  25  are fabricated with teeth  29  and  28  respectively oriented to oppose the loosening of fabric  12  and fabric  10  while they are under tension across frame  20 . 
     FIG. 2A  shows an elastic band  30  to be fitted over the fabric  10  and the frame  20 . In the second step, shown in  FIG. 2B , the fabric  10  and frame  20  are flipped over together, and the fabric  10  is secured to the frame  20 . In a third step, the fabric  10  may be drawn tightly across the fan blade frame  20 , and the tensioning means further tightened to secure the fabric  10  in its final configuration. In a fourth and final step, shown in  FIG. 2C , the fabric  10  is trimmed to eliminate any excess around the secured edges of fabric  10 . The result is a complete fan blade  50 , as shown in  FIG. 2D . 
   In some embodiments, the user may choose to leave some slack in the fabric. When the fan is operated, the slack is then taken up by the rotation of the fan against the ambient air, filling out the fan blade to its operating form. 
   As shown in  FIG. 3 , a first embodiment of the invention incorporates a retention groove  22  in the outside of the frame  20 , in which an elastic band  30  fits over the fabric to hold the fabric in place. All embodiments of the invention may incorporate stabilizing struts  45  or cross members  40  attached at various points on the frame  20  to keep the frame  20  from racking or twisting out of shape. The configuration of these stabilizing members  40  will depend on the desired size and shape of the completed fan blade  50 . 
   The invention&#39;s fan blades  50  may take any shape consistent with the need to maintain adequate tension in the fabric, and consistent with the need to circulate air effectively. A typical fan blade of the invention is elliptical in shape, as shown in  FIGS. 1 ,  2 A through  2 D, and  3 . The set of usable blade frame shapes includes, but is not limited to, circular, polygonal, concave-sided, or irregular shapes. Common convex shapes are shown in  FIGS. 3A through 3F . All of these figures show struts  45  supporting opposite sides of fan blade frame  20 . In addition to different shape embodiments, the invention&#39;s fan blades may also comprise multiple elements each of the same or different shape. The combinations of shapes and multiple fan blade elements offer many decorative possibilities to the invention&#39;s user. 
   The light weight of the invention&#39;s fan blades makes possible the fabrication and use of fan blades with large surface area. See  FIGS. 3G and 3H , showing the fan blades  50  of  FIG. 1  mounted to fan motor  80  with fan blade struts  70 . 
     FIGS. 3I and 3J  show the fan blades  50  of  FIGS. 3C and 3F  respectively mounted to fan motor  80  with fan blade struts  70 .  FIGS. 3K and 3L  show respective top and bottom views of the fan blades  50  of  FIG. 3F  mounted to fan motor  80  with fan blade struts  70 . The overlap of fan blades  50  shown in  FIGS. 3K and 3L  provides additional decorative appeal to the invention&#39;s fan&#39;s appearance. 
   In still another class of embodiments (not shown), the fabric used to form the operating surfaces of the fan blade may be cut and formed with decorative openings to appear in each blade. 
   See  FIGS. 4A through 4C . The invention further comprises a supportive band  60  which encircles the fan motor housing. Fabric  10  is stretched and secured over supportive band  60  to provide a decorative surface trim band  15  for the fan motor housing. The fabric trim band  15  on the fan motor housing may also be changed without the use of tools or other extensive procedures. One embodiment uses a supportive band  60 , such as a piece of spring steel or plastic sheet, fabricated in a curved form of slightly smaller curvature radius than the curvature radius of the fan motor housing. The fabric  10  is secured to the band  60  by means of tape or adhesive  62 . Once the fabric  10  is secured to the band  60 , the resulting fabric trim band  15  is then wrapped around the circumference of the motor housing. The supportive band  60  stays in place by means of the compression against the housing created by the tendency of the band  60  to curl to its nominal shape. 
   In an alternate embodiment, the supportive band  60  has a pre-attached magnetic strip  64  that locks onto the metal fan motor housing. In still another embodiment (not shown), the fabric-covered band  60  is attached to the housing with Velcro or other closure methods that render the band  60  easily attachable and removable. 
   In most applications, the fabric  10  on the blades is also used as the trim band on the fan body. In other applications, the fabric is used separately on either the blades or fan body, or two distinct fabrics are used on blades and fan body. 
   The invention&#39;s fan blade attaches to the fan motor in the conventional manner of ceiling fan blades. See  FIG. 5 . The fan blade frame  20  is fabricated with holes  24  for screws or bolts for fastening the fan blade frame  20  typically to a strut  70  connected to the fan&#39;s rotating shaft. 
   The embodiments of the invention shown above provide an outer compression member that compresses and hold the fabric against an outer wall of a frame with an annular shape that encloses an open space inside the annulus. Those skilled in the art understand that the structure the fabric can be held against the inner wall of the annular frame if one uses fixed fasteners (pins, screws or bolts) or an expansion member. For example, a hoop could be placed inside the frame and have its length extended to exert an outward force against the inside wall of the annular frame. The hoop could be held in place with a clamp. As an alternative, the hoop may comprise an expansion ring  200  as shown in  FIG. 6 . It has an elongated body that has either a taper or a reduced diameter at one end  204  to fit inside the opposite end.  202 . The opposite ends have spring retainer blocks  206 ,  210  and a spring  208  that is biased to push the ends apart. The circumference of the ring  200  is reduced by pressing the tapered end  204  inside the larger end  202 . The ring is set inside the frame  20  and inside the fabric  10 . Upon release of the ends, the ring expands to press the fabric  10  against the inner facing wall of the frame  20 . 
   The invention provides a decorative, lightweight, and easily changeable fan blade usable on any ceiling fan for circulating air. The fan blades of the invention have less mass than conventional fan blades and their lower mass allows for significant reductions in power consumption, stress, wear, and tear on the fan&#39;s ceiling mountings. The invention&#39;s fan blade may take any of a wide range of shapes, sizes, and structures, offering advantages of both appearance and function in comparison to conventional ceiling fans. As such, the invention may be practiced in a variety of embodiments including ones shown here and other embodiments that are insubstantial modifications of the invention as claimed herein.