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 
       [0001]    1. Field of the Invention 
         [0002]    This patent relates to a protective device for door frames. More particularly, this patent relates to a device for protecting door frames that can be installed prior to construction, renovation and moving, and then easily and quickly removed afterwards. 
         [0003]    2. Description of the Related Art 
         [0004]    During construction, renovation and moving operations key surfaces in a building can be subjected to abuse by workers and equipment moving in and around the building rooms. These surfaces, which include door frames, door edges and outer wall edges (i.e. outwardly projecting wall corners), are costly to repair and can often delay the completion of a building project. Protecting these surfaces can avoid costly repairs, reduce overall building costs and shorten building project time. 
         [0005]    Several previous attempts to provide a protective device for door frames and the like are known. For example, Weller U.S. Pat. No. 4,768,320 describes a generally U-shaped door frame guard having a rigid outer shell and a soft inner shell. The guard has a generally rectangular central section (spine) and generally straight inwardly converging side members designed to grip a wall. 
         [0006]    Freelove U.S. Pat. No. 5,203,130 describes a generally U-shaped extruded plastic door frame shield having flange-like cleats that oppose the door frame trim to hold the shield in place. 
         [0007]    Raulerson et al. U.S. Pat. No. 5,737,878 describes a U-shaped door guard made from polymeric material and having side members that taper toward each other and can grip a doorway. 
         [0008]    Hill U.S. Pat. No. 5,775,045 described a magnetic door frame guard to be used with metal door frames. 
         [0009]    Wamsher U.S. Pat. No. 5,815,998 describes a resilient, U-shaped, door jamb protector comprising a high density plastic core sandwiched between soft plastic foam material. 
         [0010]    Haldeman U.S. Pat. No. 6,357,187 describes a cardboard door frame protector that encloses the door frame without contacting it. 
         [0011]    Hartley et al. U.S. Pat. No. 6,526,708 describes a guard that is attached to a door frame with a clamp. 
         [0012]    Stradel U.S. Pat. No. 6,826,877 describes a guard for protecting a door frame having trim molding. The guard comprises a planar web (spine) and parallel side panels normal to the spine that flex toward each other. At least one of the side panels has an inwardly directed shoulder with a transverse flange that seats against a rear facing surface of the door trim molding. 
         [0013]    Lovas U.S. Pat. No. 6,829,863 describes a guard that is attached to a door jamb via metal spring strips. 
         [0014]    Mayes U.S. Patent Application Publication No. 2004/0088933 describes a C-shaped door trim guard having ridges for gripping the door trim. 
         [0015]    It is an object of the present invention to provide an alternative means for protecting building surfaces, particularly door frames, that are vulnerable to abuse by workers and equipment. 
         [0016]    Another object of the invention is to provide a protective device for building surfaces that does not require adhesive and is easy to install and remove. 
         [0017]    Further and additional objects will appear from the description, accompanying drawings, and appended claims. 
       SUMMARY OF THE INVENTION 
       [0018]    The present invention is a guard for protecting a door frame from impacts caused by people and equipment. The guard is a formed and cut paperboard tube comprising a longitudinal spine and two curvilinear, elongated, resilient side members attached to the spine. Each side member terminates in a free edge running parallel to the spine. The free edges are adapted to grip opposite sides of the door frame or the wall when the guard is placed over the door frame. No tape or other means of securing is required. Each side member further comprises a longitudinally disposed bead for added impact resistance. The guard may be manufactured by winding paperboard into a hollow longitudinal tube, forming the tube into the desired curvilinear shape, and making a longitudinal cut along the tube. 
     
    
     
       THE DRAWINGS 
         [0019]      FIG. 1  is a perspective view of a door frame guard according to the present invention. 
           [0020]      FIG. 2  is a top perspective view of the door frame guard of  FIG. 1  shown protecting a door frame. 
           [0021]      FIG. 3  is a side plan view of the door frame guard of  FIG. 1  shown protecting a door frame. 
           [0022]      FIG. 4  is a close up perspective view of the door frame guard of  FIG. 1  shown protecting a door frame. 
           [0023]      FIG. 5  is a cross sectional view of the door frame guard of  FIG. 1 . 
           [0024]      FIG. 6  is a cross sectional view of the door frame guard of  FIG. 1  shown installed over a door frame. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0025]    While this invention may be embodied in many forms, there is shown in the drawings and will herein be described in detail one or more embodiments, with the understanding that this disclosure is to be considered an exemplification of the principles of the invention and is not intended to limit the invention to the illustrated embodiments. 
         [0026]    Turning to the drawings, there is shown in  FIG. 1  one embodiment of the present invention, a guard  10  for protecting door frames and other building surfaces. The guard  10  comprises a longitudinal spine  12  and two opposing, substantially U-shaped, curvilinear, elongated, resilient side members  14  connected to each other along the spine  12 . Each side member  14  terminates in a longitudinal free edge  16  that is substantially parallel to the spine  12 . The resilient nature of the guard  10  causes the side members  14  to be biased toward each other when the side members  14  are flexed outwardly (away from each other). 
         [0027]    More particularly, each U-shaped side member  14  comprises an outer wall segment  18  and an inner wall segment  20  connected at an outer apex  22 . The inner wall segment  20  extends from the outer apex  22  to the free edge  16 . The outer wall segment extends from the outer apex  22  to the spine  12 . 
         [0028]    Optional beads  24  may be longitudinally disposed in each outer wall segment  18  for added impact resistance and to enhance the spring-like characteristics of the guard  10 . The spine  12  itself may be curved inwardly—in the direction of the inner wall segments  20 —to further enhance the spring-like characteristics of the guard  10 . 
         [0029]    In its relaxed, unstressed condition, the distance (D) between the free edges  16  of the guard  10  preferably is less than the thickness of the wall to which the door frame is mounted. Consequently, when installing the guard  10  around a door frame affixed to a wall having a thickness greater than (D), the side members  14  must be flexed outwardly, away from each other. This is typically done by hand. When released, the free edges  16  grip either side of the wall  20  to hold the guard  10  in place without the need for further securing means. 
         [0030]      FIGS. 2-4  are views of a guard  10  shown installed over a door frame  26 . When the guard  10  is placed over the door frame  26  to cover and protect it, the side members  14  are in a stressed, spread apart, state. The guard  10  covers the door frame  26  along its length, and preferably along that part of its length most likely to be subject to abuse from people and equipment. 
         [0031]    Of course, the guard  10  can be made to any length to cover as much of the door frame  26  as desired. The guard  10  may be made wide enough and resilient enough to accommodate various door frame and wall thicknesses. 
         [0032]      FIG. 5  is a cross sectional view of an edge guard  10  according to the present invention showing the distance (D) between the free edges when the guard  10  is in an unstressed position. The side members  14  are generally U-shaped and are connected at the inwardly curved spine  12 . The outer and inner wall segments  18 ,  20  of each side member  14  meet at an outer apex  22 . 
         [0033]      FIG. 6  is a cross sectional view of the edge guard  10  of  FIG. 5  shown installed over a door frame  26 . The guard  10  is now in a stressed state and the free edges  16  are spread apart a distance greater than (D). The free edges  16  are in contact with the wall  30 . 
         [0034]    The guard  10  may be made from any suitable material, including plastic or metal, but preferably is made from paper or, more specifically, layers of paperboard laminated together. 
         [0035]    The guard  10  may be manufactured by winding paperboard into a hollow tube, forming the tube into the desired curvilinear shape, and then making a longitudinal cut along the tube opposite the spine  12 . 
         [0036]    It is understood that the embodiments of the invention described above are only particular examples which serve to illustrate the principles of the invention. Modifications and alternative embodiments of the invention are contemplated which do not depart from the scope of the invention as defined by the foregoing teachings and appended claims. It is intended that the claims cover all such modifications and alternative embodiments that fall within their scope.

Summary:
A guard for protecting a door frame is provided. The guard is a formed and cut paperboard tube comprising a longitudinal spine and two curvilinear, elongated, resilient side members attached to the spine. The side members terminate in free edges adapted to grip opposite sides of the door frame wall. Each side member further comprises a longitudinally disposed bead for enhanced impact resistance.