Patent Document

CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application No. 60/586,135, filed Jul. 7, 2004, the contents of which are incorporated fully herein. 
    
    
     FIELD OF THE INVENTION 
     The present invention is related generally to adjustable footrests, more particularly, to a footrest having an integral two-stage heater for directing streams of heated air onto the feet of a user. 
     SUMMARY OF THE INVENTION 
     The present invention provides a footrest for supporting and heating a user&#39;s foot. The footrest includes a footplate for receiving a user&#39;s foot, and a warm air delivery system. The warm air delivery system uses a fan to draw ambient air from the environment into the a housing of the footrest through a cold air intake. The fan then propels the ambient air down a heating channel in which resides a heating element. After traversing and being warmed by the heating element, the now warm air continues down the heating channel and exits the housing of the footrest at a warm air exhaust. The footrest is provided with a warm air shield for redirecting the heated air expelled from the warm air exhaust onto a user&#39;s foot. 
     In preferred embodiment of the present footrest, the fan provided for drawing ambient air into the housing of the footrest is a quiet radial fan. In another preferred embodiment, the heating element is a two stage heater comprising a coil of nichrome wire wrapped around insulating mica boards. 
     A high/low heat switch is provided for varying the amount of heat generated by the heating element, and thus the temperature of the air directed at a user&#39;s feet. This high/low heat switch may be mounted on the footplate so that a user of the footrest can control the setting of the switch using her foot. Additionally, the footplate can be made to pivot along an axis to provide a desired angle for a user of the footrest. 
     Safety devices may be provided as part of a wiring harness of the present footrest, such as a ground fault interrupt device and a safety cut-off switch, to prevent accidental burns or shocks to a user of the footrest. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an oblique perspective of an exemplary embodiment of the footrest with integral heater of the present invention; 
         FIG. 2  is an overhead view of the exposed interior of the base of the footrest shown in  FIG. 1 ; 
         FIG. 3  is an overhead view of the base shown in the previous figure depicts the addition of a cover plate over the previously exposed heating channel; 
         FIG. 4  shows multiple overhead views of the exposed interior of the base of the footrest of  FIG. 2 . 
     
    
    
     Before any embodiment of the invention is explained in detail it is to be understood that the invention is not limited in its application to the exemplary details of construction and arrangements of components set forth in the following description or illustrated in the drawings. The invention is capable of alternative embodiments and of being practiced or being carried out in various ways. Also, it is to be understood that the terminology used herein is for the purpose of illustrative description and should not be regarded as limiting. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Now referring to the figures,  FIG. 1  shows an oblique view of an exemplary embodiment of the footrest with integral heater of the present invention. The footrest includes a base  1  having a cold air intake  3 , a base housing  2  and the components contained therein (shown in more detail in the following figures) for receiving a mass of cold air through the cold air intake  3  and heating and expelling a mass of warm air. Vectors  8  indicate the mass of cold air being drawn into the cold air intake  3 , shown in the foreground of  FIG. 1 . Once the mass of cold air is drawn into the base  1  of the footrest and heated to a desired temperature, it is expelled as a mass of warm air from a warm air exhaust on the rear of the base  1  (not visible in  FIG. 1 ). Vectors  9  indicate the origin and direction of travel the mass of warm air. 
     A footplate  10  is provided attached to the base  1  of the footrest using one or more mounting devices  5 , as shown in  FIG. 1 . The footplate  10  is provided to support one or both feet of a user, and may be provided with multiple friction elements  11  allowing the footplate  10  to better grip the user&#39;s feet. The footplate  10  may be provided with the general shape of an outline of a pair of human feet. 
     The footplate  10  may also be provided with an adjusting mechanism allowing it to pivot around an axis formed by the mounting devices  5  shown in  FIG. 1 . In one embodiment, the adjusting mechanism comprises a flexible washer around each mounting device  5 . The footplate  10  may be only loosely connected to the base  1  using the mounting devices  10 . When the angle of the footplate  10  is depressed slightly, for example by the weight of a user&#39;s foot, the elastic properties exhibited by the flexible washers in compression exert a reaction force on the footplate  10  balancing the downward force of the user&#39;s foot. This is but one embodiment; other provisions for an adjusting mechanism for the footplate  10  will be known to those skilled in the art. 
     One or more mounting brackets  6  are provided attached to the base  1  of the footrest. The mounting brackets  6  are used to attach a warm air shield  15  to the base  1 . The warm air shield is provided to allow for the redirection of the mass of warm air onto the feet of a user of the footrest. The vectors  9  show the mass of warm air being redirected along the interior concave surface of the warm air shield  15 , from an initially vertical direction when the vectors  9  exit the base  1  of the footrest to a partially downward direction towards the footplate  10 . In this manner, a user who places her feet on the footplate  10  may have them warmed by the redirected mass of warm air represented by the vectors  9 . 
     It should be understood that the design of the warm air shield  15  shown in  FIG. 1  is exemplary only and that a variety of interior surfaces may be provided for the warm air shield  15  in order to produce varying orientations of the vectors  9  indicating a mass of warm air directed over the feet of a user of the footrest. 
     The warm air shield  15  may additionally incorporate a series of recesses  16  as shown in  FIG. 1  for aesthetic and/or functional purposes. In the embodiment shown, the recesses  16  are placed so as to allow a greater clearance between the warm air shield  15  and the footplate  10 , allowing a user of the footrest to more easily place her foot on the footplate  10  without the instep of the foot coming into contact with the warm air shied  15 . 
       FIG. 2  depicts an interior view of the base  1  of the previous figure. The base  1  includes a base plate  29 , having mounting brackets  26  for facilitating the attachment of the base housing  2  shown in the previous figure to the base plate  29  of the base  1 . 
     Mounted on the base plate  29  is a radial fan  21  adjacent to a heating element  23 , which is itself adjacent to a heating channel  22 . Ambient air is drawn into the base  1  from the environment through the cold air intake  3  by the radial fan  21 . The airflow generated by the radial fan  21  is forced through the heating channel  22 , in which resides the heating element  23 , shown to the left of the radial fan  21  in  FIG. 2 . Vectors  8  indicate a mass of cold air being drawn into the radial fan  21  and expelled across the heating element  23  in the heating channel  22 . As the mass of cold air traverses the heating element  23 , it warms and continues to travel down the heating channel  22 . 
     The heating channel  22  terminates at a warm air exhaust  28 . The warm air exhaust  28  is matched to a gap in the base housing  2  covering the base  1 . Vectors  9  indicating the path of a mass of warm air as it travels through the warm air exhaust  28  to pass through the gap in the base housing  2 , to be redirected onto the feet of a user of the footrest by the warm air shield  15  of  FIG. 1 . Exhaust fins  27  are provided in the warm air exhaust  28  to more evenly distribute the passage of the mass of warm air along the warm air exhaust  28  from the heating channel  22 . 
     The exemplary embodiment of  FIG. 2  shows the channel  22  fabricated from sheet metal bent, stamped and/or cut to form the desired channel shape.  FIG. 2  also shows a series of screw holes  25  formed in the structure of the channel  22 . These screw holes allow a cover (not shown in  FIG. 2 ) to be placed over the channel  22 , confining the passage of the mass of warm air between the heating element  23  and the warm air exhaust  28  to the channel  22 . As shown in more detail in the following figure, the cover may be placed over the channel  22  and secured with sheet metal screws. Alternative methods of attachment may be available, as is know to those skilled in the art. 
     In an exemplary embodiment of the present footrest, the heating element  23  comprises a two-stage heater, similar to the type of heater found in home hair drying equipment. The heating element  23  may be more specifically comprised of bare, coiled nichrome wire wrapped around insulating mica boards. As is known to those skilled in the art, nichrome wire is an alloy of two metals, nickel and chromium. Nichrome wire is a desirable choice for a filament of the heating element  23  because of its conductive properties, and because unlike ferrous or other metals, it fails to oxidize when heated. As an alternative embodiment, heating element  23  may comprise a solid resistive heating element outfitted with a heat sink. 
     When the mass of cold air is initially propelled into the heating channel  22  by the radial fan  21 , it is much cooler than the nichrome wire of the heating element  23 . Due to this fact, heat flows from the nichrome wire to the mass of cold air. How hot the mass of cold air passing over the heating element  23  becomes is dependent in large part on the power supplied to the heating element  23 . The higher the wattage, the more heat is generated in the heating element&#39;s coils and transferred to the mass of cold air. 
     The mass of cold air becomes heated immediately after passing over the heating element  23  and a mass of warm air is produced preferably moderately heated so that, while the mass of warm air is comfortable and soothing when directed at the feet of a user, it is not so hot as to be uncomfortable or dangerous. 
     When mass of cold air is drawn into the base  1  of the footrest by the radial fan  21 , foreign particles may be pulled towards the cold air intake  3 . To prevent particles above a certain size from entering the base  1 , a wire screen is provided as part of the cold air intake  3 . Without this screen, lint or other contaminants may build up inside the base  1  and be scorched by the heating element  23 , or they may clog the radial fan  21  itself. An excess of these contaminants inside the base  1  can also partially block the airflow into the heating channel  22 , potentially causing the heating element  23  to overheat due to the lessened airflow available to carry away the heat generated by the coils of nichrome wire. 
     In the footrest depicted in  FIGS. 1 and 2 , the base housing  2  may serve not only as a structural component of the footrest and to protect the component parts contained therein, but also to insulate the heating element  23  from transferring its heat directly to the base housing  2  and through it to the footplate  10 . An arch in the base housing  2  further distances the footplate  10  and with it the user&#39;s feet from the heating element  23 . In this manner the user&#39;s feet will be heated by the mass of warm air expelled from the warm air exhaust  28  (represented by vectors  9 ), rather than by a conductance of heat directly to the footrest  10  itself. 
       FIG. 2  shows a wiring harness  24  comprising a power cord and other necessary components for providing current to the radial fan  21  and the electric heater  23 . Proper composition and arrangement of these components are known to those skilled in the art. A high/low heat switch  20  may be supplied as part of the wiring harness  24 . This switch allows a user of the footrest to determine whether a greater or lesser amount of electrical power will be dissipated as heat by the heating element  23 . 
     In an alternative embodiment, the high/low heat switch  20  may be provided mounted (in a manner not shown) on the footplate  10  shown in  FIG. 1 . The high/low heat switch  20  may additionally be mounted in a fashion allowing a user to select a desired heat setting using her foot. 
     In a further embodiment, the footrest may be provided with certain safety features to protect a user from burns or electrical shock. One feature comprises a safety cut-off switch included in the wiring harness  24 . This safety cut-off switch (not shown) ensures that the mass of warm air expelled by the warm air exhaust  28  never exceeds a temperature above which it could possibly burn the skin of a user of the footrest. The safety cut-off switch may comprises a temperature sensitive device such as a bimetallic strip which would interrupt the flow of current to the heating element  23  when the temperature inside the heating channel  22  exceeded a certain limit. 
     The wiring harness  24  shown in  FIG. 2  may also include a ground fault interrupt device (also not shown). As is known in the art, the ground fault interrupt device will trip and stop a flow of current through a pair of lines if it senses an imbalance between the current flowing in the hot and neutral lines. In this manner, were the wiring harness  24  to become improperly grounded and cause a potentially dangerous situation, the ground fault interrupt device would trip before significant harm could be caused. 
       FIG. 3  shows an overhead view of the base  1  of the footrest from  FIG. 2 , with the addition of a cover plate  30  over the previously exposed heating channel  22 . A series of screws  31  are provided corresponding to the screw holes  25  of the previous figure. With the cover plate  30  attached to the heating channel  22  using the screws  31 , an enclosed and relatively airtight passage is created between the radial fan  21  and the warm air exhaust  28 . In this manner the radial fan can create a zone of high pressure at the beginning of the heating channel  22  forcing air across the heating element  23  and out the warm air exhaust  28 . 
       FIG. 4  depicts multiple overhead views of the exposed interior of the base  1  from  FIG. 2 . These views better depict the details of various components of the present footrest, including the cold air intake  3 , high/low heat switch  20 , radial fan  21 , heating channel  22 , heating element  23 , wiring harness  24 , mounting bracket  26 , warm air exhaust  28  and the base plate  29 . 
     Heretofore the invention has been discussed having a radial fan  21  for moving a mass of air through the footrest. A radial fan preferred given its quiet operation. However, alternatives exist to the radial-type are known in the art. In a series of alternative embodiments, a medium or high speed radial, axial, or drum type fan, a duct propeller fan, or a blower type fan driven by an electric fan motor may be provided in the present footrest. 
     The radial fan  21  preferably includes either an AC or a DC motor, which is directly coupled to the impeller of the radial fan  21 . The motor may be electrically coupled to a conventional switch, included as part of the wiring harness  24 , for turning the radial fan  21  on and off. This switch (not shown) may include multiple settings for various speeds which produce various air velocities for the mass of cold air propelled into the heating channel  22 . In an embodiment of the present footrest, the heating element  23  is electrically coupled to the radial fan  21  by the wiring harness  24  so that a common switch (not shown) activates each of the radial fan  21  and the heater element  23 . In another exemplary embodiment, the radial fan  21  and the heater element  23  may be separately controlled to disable the heating element  23  when the radial fan  21  is being operated so as to circulate a mass of cold air over the feet of a user of the footrest. 
     In further alternative embodiments of the present footrest, the user&#39;s foot may be heated by means other than heated air, such as by directing streams of steam to the user&#39;s foot or heating the footplate  10  itself. These heating means may be used in addition to or instead of the heating arrangements described above in reference to  FIGS. 1–4 . 
     In another alternative embodiment of the present footrest, a pair of footplates are provided 10, one to receive each foot of a user of the footrest. 
     It will be understood that various modifications can be made to the disclosed embodiments of the present invention without departing from the spirit and scope thereof. Therefore, the above description should not be construed as limiting the invention, but merely as an exemplification of preferred embodiments of the invention. Those skilled in the art will envision other modifications within the scope and spirit of the present invention.

Technology Category: 1