You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a stabilizer for a folding step ladder such that the feet of the ladder do not spread laterally or transversely from the weight and movement of a user on the ladder. 
   2. Brief Description of the Prior Art 
   It is known to incorporate braces into ladders, such as folding step ladders. The bracing may be added to increase ladder strength and to prevent twisting and flexing of the ladder. Other conventional bracing may be used to provide a stable footing for the ladder so that it will remain in place when placed on uneven ground. Also, some forms of conventional bracing may be used to provide an anti-slip contact surface on the ladder feet. 
   The following U.S. patents are incorporated by reference herein: U.S. Pat. Nos. 141,126, 2,634,037, 5,141,076, 5,370,204, 5,417,302, 5,791,435, 5,791,438, 6,116,379 and 6,419,047. 
   BRIEF SUMMARY OF THE INVENTION 
   The feet of an ordinary folding step ladder tend to slip laterally and transversely under the weight and movement of a user. In construction of housing and other buildings it is often more convenient or expedient to install floor tile or other flooring before the electrical, plumbing or ceiling installations are completed. When the flooring is secured by an adhesive, such as a conventional mastic, it will be several days after installation before the mastic is completely cured and the floor tile or other flooring is securely fastened to the substrate. 
   If a ladder is placed on an uncured floor, during completion of the installation of electrical wiring for example, the feet of the ladder will move against the floor tile or other flooring in response to movement of a user in climbing or working on the ladder. The movement of the ladder&#39;s feet may push the floor tile or other flooring out of position or may loosen it. This dislocation of the floor tile or other flooring can result in an unsightly surface and require the flooring installer to be called back to correct the damage. Even if the mastic is set, other damage may be done by sliding a ladder across the floor because the legs tend to grab the flooring making the ladder bounce, chatter and dance across the floor. This may mar the flooring, catch a seam of carpeting or cause other damage. 
   A folding step ladder outfitted with the stabilizing device of the invention has increased stability, particularly on surfaces that may shift in response to movement of a ladder&#39;s feet. The stabilizing device of the invention reduces movements of a ladder&#39;s feet during use. In particular, the device of the invention resists movement of the ladder&#39;s feet by providing a structure which operates adjacent to the ladder&#39;s feet to provide a resistive force to the incipient movement of the ladder&#39;s feet. The structure provides resistive forces to incipient transverse and longitudinal movement and to torsional forces which are experienced at the feet of the ladder. 
   In view of the above, it is an object of the present invention to provide a stabilizing device for a folding step ladder that resists incipient movement of the feet of the ladder during use. It is another object to provide a stabilizing device for a folding step ladder which tends to prevent floor damage by the legs of the ladder when the ladder is used or slid across the floor. Other objects and features of the invention will be in part apparent and in part pointed out hereinafter. 
   The invention summarized above comprises the constructions hereinafter described, the scope of the invention being indicated by the subjoined claims. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
     In the accompanying drawings, in which several of various possible embodiments of the invention are illustrated, corresponding reference characters refer to corresponding parts throughout the several views of the drawings in which: 
       FIG. 1  is a perspective view of a erected ladder incorporating a stabilizing device in accordance with the present invention; 
       FIG. 2  is a perspective view of the ladder of  FIG. 1  in a partially retracted position; 
       FIG. 3  is a back plan view of the ladder of  FIG. 1  in a fully retracted position; 
       FIG. 4  is a right side view of the ladder shown in  FIG. 3 ; 
       FIG. 5  is a partial cross-sectional view of the ladder and device of the invention taken along the plane V—V, shown in  FIG. 1  and additionally showing detachable pads; 
       FIG. 6  is a partial cross-sectional view of the ladder and device of the invention taken along the plane VI—VI, shown in  FIG. 2 ; 
       FIG. 7  is a partial cross-sectional view of the ladder and device of the invention taken along the plane VII—VII, shown in  FIG. 3 ; 
       FIG. 8  is a bottom plan view of the device of the invention; and, 
       FIG. 9  is a bottom plan view of an alternative embodiment of the device of the invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to  FIGS. 1 and 2 , a folding step ladder  10  is shown. Ladder  10  may be made of wood or other material and is shown as a conventional metal ladder, such as an aluminum ladder, and is modified as is disclosed herein. Ladder  10  has a pair of front legs  12  which are equipped with steps  14  extending transversely therebetween. Ladder  10  also has a pair of back legs  16 , as shown. As is known in the art, ladder  10  may also have a paint platform, not shown. 
   Front legs  12  and back legs  16  extend to a top cap or platform  18  to which they are joined. Back legs  16  pivot about a pivot pin  19  connected to top cap or platform  18  such that they fold against front legs  12 , as shown in  FIGS. 2 and 4 . Front legs  12  are also connected to back legs  16  by a pair of folding spreader braces  20 . Folding spreader braces  20  may be selectively locked to hold ladder  10  in the fully erected position shown in  FIG. 1  and may also be pivoted out of locking position to allow ladder  10  to be folded, to be stored for example, as shown in  FIGS. 2 and 4 . 
   As shown in  FIGS. 1 and 2 , back legs  16  may have transversely extending braces  22  for additional strength or may have cross bracing, not shown, as is known in the art. Front legs  12  terminate in a pair of feet  24 . Back legs  16  terminate in a pair of feet  26 . Front feet  24  and back feet  26  may be supported by the stabilizing device of the invention, as described more fully herein. In addition, front legs  12  and back legs  16  may be provided with additional angle braces  28 ,  29 ,  30  and  31 . Angle braces  28  and  29  are shown in  FIGS. 1 ,  2  and  3  as attached to the front legs  12  and the top and bottom transverse step members  14 . Angle braces  30  and  31  are shown in  FIG. 3  as attached to back legs  16  and top and bottom transverse braces  22 . 
   As shown in  FIGS. 1 ,  2 ,  5  and  6 , ladder  10  is equipped with a stabilizing device of the invention, shown as element  32 . Stabilizing device  32  has two rectangular frames  34  and  36  which are pivotally joined in the middle by a hinge, for example a piano hinge  38 , which is connected to center transverse members  40  and  42  of rectangular frames  34  and  36 , respectively. Rectangular frames  34  and  36  also have distal transverse members  44  and  46 , as shown. Distal transverse members  44  and  46  are pivotally joined to inner transverse members  48  and  50  by hinges, for example piano hinges  52  and  54 , as shown in  FIGS. 5 and 6 . Piano hinges  38 ,  48  and  50  have a high degree of rigidity which this type of hinge provides, however, other hinge structures may also be used. Longitudinal members  55  complete rectangular frames  34  and  36 . It will be appreciated by those skilled in the art that rectangular frames  34  and  36  may also be formed of rectangular sheets, and the like. 
   As shown in  FIGS. 1 and 5 , distal member  44  spans back legs  16  and may have receivers  56  at opposite ends thereof. Receivers  56  receive ends  26  of legs  16 , as shown. Receivers  56  may have flanges  58  which extend upwardly and lie adjacent lateral sides of legs  16 , as shown in  FIGS. 1 and 2 . Flanges  58  may be attached directly to legs  16  of ladder  10  by conventional adhesives and/or fasteners, such as screws, rivets or bolts, to provide a firm, stable attachment, with or without first removing the end caps normally attached to the ends of ladder legs  16 . 
   Distal transverse member  46  spans front legs  12  and may have receivers  62  at opposite ends of distal transverse member  46 , as shown. Receivers  62  may have flanges  64  which extend upwardly and lie adjacent lateral sides of legs  12 , also as shown in  FIGS. 1 and 2 . Flanges  64  of receivers  62  may be attached directly to legs  12  of ladder  10  by conventional adhesives and/or fasteners, such as screws, rivets or bolts, to provide a firm stable attachment. 
   As shown in  FIGS. 3 through 9 , some or all of transverse members  40  through  50 , may have a protective material  68  attached to the under surface of those members. Protective material  68  may be any of a variety of cushioning and/or anti-slip materials. Suitable materials for protective material  68  include foam rubbers and foamed plastics such as polyether foam, polyurethane foam and equivalent materials. Other materials may also be used such as plastic and rubber sheet, carpeting or other textiles. Protective material  68  may also be made of nylon or the like such that ladder  10  slides easily or as shown in  FIG. 5  of a combination of materials. With continuing reference to  FIG. 5 , protective material  68  may include a female attachment member such as the pile side of a VELCRO fastener and a detachable pad  69  formed of a slippery material such as nylon attached with a male attachment member like the hook side of a VELCRO fastener. When the pile side is exposed, ladder  10  can be slid across a tile floor, for example, and when detachable pad  69  is attached, ladder can be easily slid across a carpeted area. While male and female attachment members are shown, it will be understood that detachable pad  69  may be hinged to stabilizer device  32  or otherwise attached with means for selective deployment. 
   As shown in  FIGS. 1 through 3  and  5  through  7 , stabilizing device  32  has a retractor  70  attached near the center of stabilizing device  32  and connected to a point on ladder  10  such as the underside of top cap or platform  18 , as shown. Retractor  70  may be a light chain, as shown, or a cord or other conventional flexible material, as is known in the art. Retractor  70  permits stabilizing device  32  to be folded around hinges  38 ,  52  and  54 , by upward motion of retractor  70 , as ladder  10  is folded to the closed position. Retractor  70  may add convenience to the use of stabilizing device  32 , however, it will be appreciated by those skilled in the art that stabilizing device  32  may folded by lifting the center of stabilizing device  32  by hand or with a foot. The portion of cushioning or anti-slip material  68  under transverse member  42 , or under transverse member  40 , if used, protects stabilizing device  32  from damage and also permits stabilizing device  32  to be conveniently folded by placing a hand or foot under the center of the stabilizing device  32  and lifting the center of the stabilizing device  32 . 
     FIG. 9  shows an alternative stabilizing device  72 . The stabilizing device  72  has two trapezoidal frames  74  and  76 , as shown. The trapezoidal frames have a plurality of transverse members, for example those shown as elements  78 ,  80 ,  82 ,  84 ,  86  and  88  which are analogous to the transverse members previously described for rectangular frames  34  and  36 . Trapezoidal frames  74  and  76  have longitudinal members  90 , which are angled in to fit more closely within the angled legs of ladder  10 . It will be appreciated by those skilled in the art that trapezoidal frames  74  and  76  may also be formed of a solid sheet, as described above. 
   When ladder  10  is erected without stabilizing device  32  (or  72 ), a downward force on step  14 , for example bottom step  14 , flexes the center of the step downwardly. This flexure creates an incipient transverse movement of feet  24  which may displace tiles (or other flooring) on which ladder  10  is resting. In addition, as a user progresses up ladder  10  the downward force from the user&#39;s weight is moved toward the center of the ladder flexing the ladder and creating an incipient longitudinal movement of feet  24  and  26 , which movement may also displace tiles on which ladder  10  is resting. It will be appreciated that during use of ladder  10  the movement of a user on the ladder will also create further translational and torsional forces on the ladder which will be transferred to feet  24  and  26 . 
   When ladder  10  is erected with stabilizing device  32  (or  72 ) in place, the terminal extremities of feet  24  and  26  of legs  12  and  16  are held against lateral and transverse movement in response to forces on the ladder, from the weight and movement of the user for example. Transverse members  44  and  46  resist transverse displacing movements and longitudinal members  55  resist longitudinal displacing movements. Further, stabilizing device  32  may act as a shear panel to resist displacing movements resulting from torsional forces exerted on ladder  10  and transferred to feet  24  and  26  of legs  12  and  16 . With stabilizing device  32  installed, the forces exerted on a floor on which the ladder  10  is used are essentially vertical forces. Ladder  10  may be used, and work performed using ladder  10 , on tiled floors which have been recently installed, and for which the adhesive has not cured. Ladder  10  will not displace the tiles and prevents damage to the tiled floor which would require further work to repair the damage. 
   As will be appreciated by those skilled in the art, stabilizing device  32  (or  72 ) may be made by a variety of conventional methods and of a variety of conventional materials. Stabilizing device  32  may be made of metal, for example aluminum, wood, or plastic materials, for example nylons, polypropylenes, polyethylenes or similar materials. Stabilizing device  32  may be made by laying up elements of the device and joining the elements by conventional fasteners and/or adhesives. Stabilizing device  32  may be welded if the appropriate materials, such as metals, are used. In addition, stabilizing device  32  may be made, by conventional molding, stamping and cutting techniques, as a few unitary pieces which require only joining by hinges and the like and the addition of cushioning and anti-slip padding  68 . It will also be appreciated that with conventional molding techniques, for plastics and the like, that stabilizing device  32  can be produced with the hinges molded in with the other structural components. 
   It will be understood by those skilled in the art that the description given herein are for purposes of illustration. For example, while the use of the ladder and stabilizing device of the invention is described in relation to its use over freshly installed flooring, the ladder and stabilizing device of the invention may be used for many purposes in which stability of a ladder is desired. The structure disclosed herein may be further modified without departing from the spirit of the invention. The invention disclosed herein is not to be limited to the embodiments disclosed herein by way of example, but only by the scope of the appended claims and their equivalents.

Summary:
A ladder is equipped with a stabilizing device. The stabilizing device resists movements of the ladder&#39;s feet which would occur in response to movements of a ladder&#39;s user while on the ladder. The stabilizing device holds the ladder&#39;s feet and provides transverse and longitudinal structure to provide counter forces to the ladder&#39;s feet to hold the ladder&#39;s feet against movement. The stabilizing device may have rigid bars forming a box structure extending between the ladder&#39;s feet or may be formed as a solid panel. The stabilizing device may be retrofitted to existing ladders.