A snow guard for a shingled roof in which the flat attachment strap positionable between layers of shingles has mounted thereon a detachable mounting bracket that projects upwardly from the attachment strap. The body portion of the mounting bracket has a wedge-shaped receptacle on the top surface to mount devices such as a snow guard attachment, which can be locked into place on the mounting bracket by a threaded fastener that passes through the mounting bracket into the base of the snow guard attachment. The snow guard attachment can be easily replaced with aesthetically different snow guard members or a snow fence that spans across several aligned mounting brackets.

BACKGROUND OF THE INVENTION 
     This invention relates generally to a snow guard for attachment to a shingled roof and, more particularly, to a mounting bracket and snow guard attachment that replicates a raised seam roof snow guard. 
     Raised seam roofs are formed with panels manufactured from sheet metal or other suitable building materials with a flat panel that runs from the peak of the roof to the lower edge thereof. These panels are joined together by a formed edges that projects upwardly above the flat surface of the panel. The formed edges of adjacent panels are interlocked to fix the panels together in a sealed seam that is raised above the otherwise planar surface of the panels. Clips can be connected to the raised seams to tie into the frame structure of the building immediately beneath the seams, thereby fixing the roofing material which the panels form to the building. The sealed seams and the lower planar surfaces of the panels provide a watertight barrier against moisture provided that the panels, including the raised seams, are not punctured. Attaching devices to a raised seam roof without puncturing the panels or the sealed raised seams is a problem that has been appreciated for many years. 
     Raised seam roofs with the planar surfaces running from the roof peak to the roof edge do not retain snow on the roof surface as any accumulated snow tends to slide downwardly along the planar surfaces, particularly after the snow has partially melted to form a moisture layer between the roof panels and the accumulated snow. One of the most frequently needed devices to be attached to raised seam roofs is a snow guard which is operable to restrict the movement of accumulated snow off the roof panels. Other devices are often needed to be mounted on the roof, such as lightening rods, antennas, or support structures for both people and other apparatus such as air conditioners, etc. A device that can engage the raised seam roof to permit such devices to be mounted thereon without causing the roof or the raised seam thereof to be perforated has been contemplated for many years. 
     One of the early mechanisms for mounting devices on raised seam roofs can be found in U.S. Pat. No. 1,330,309, issued to R. T. Dixon on Feb. 10, 1920. The Dixon mechanism includes an elongated channel member having a cavity formed therein to receive the raised seam portion of the roof panel structure. A mounting bolt is received within a transverse threaded bore to engage the raised seam portion within the cavity of the channel member to deform the raised seam into a formed pocket, thereby affixing the channel member to the raised seam portion of the roof. A board rest member is formed as part of the channel member to permit the detachable mounting of devices, such as a snow guard, to the channel member. 
     A number of patents, including U.S. Pat. No. 5,228,248; U.S. Pat. No. 5,483,772; U.S. Pat. No. 5,491,931; U.S. Pat. No. 5,983,588; and U.S. Pat. No. 6,164,033 were issued to Robert M. M. Haddock for a mounting member that, like the Dixon patent, is affixed to the raised seam portion of a roof structure without puncturing the surface of the roof panels by a fastener that engages and deforms the raised seam portion. The Haddock mounting members typically require two fasteners for stability and are formed with cavities extending through the body of the mounting member to attach devices, such as a snow fence or decorative attachments, to the mounting member. 
     U.S. Pat. No. 5,282,340; U.S. Pat. No. D364,338; U.S. Pat. No. D372,421; and U.S. Pat. No. 5,522,185 were issued to Roger M. Cline, et al. for various configurations of snow guards which are formed to be mounted on the raised seam portion of a roof structure. Like the Dixon and Haddock patents, the mounting of the snow guard involves the utilization of a fastener that is threaded into a body portion of the snow guard to engage and deform the raised seam portion of the roof structure to affix the snow guard to the roof. The snow guard structure includes a transversely extending body manufactured in a formed shape to present an esthetically pleasing device to be exposed on the surface of the roof. 
     U.S. Pat. No. 884,850, issued on Apr. 14, 1908, to F. A. Peter, is directed to a snow guard having a body member that straddles a raised seam portion of a roof to mount the snow guard without piercing the surface of the roof or the seam structure. The body member is formed in two opposing halves and is clamped onto the raised seam by a bolt that passes above the seam to interengage the opposing sides of the body member and effect a clamping action on the seam structure. While the Peter mechanism does not cause a deformation of the raised seam structure of the roof, the clamping action is indirect and does not provide a substantial affixation of the snow guard to the roof structure. 
     Shingled roofs, such as is found on conventional house roofs, do not have the raised seam structure that is prevalent in the aforementioned raised seam roof construction. Shingled roofs are formed from overlapping advancing layers of fiberglass, asphalt, plastic, slate, wood, metal or other composite material shingles that are applied to a roof structure. As is shown in U.S. Pat. No. 2,079,768, granted to David Levow on May 11, 1937, snow guards for shingled roofs are formed with a flat attachment strap that is positioned between the layers of shingles and nailed to the roof structure. As seen in U.S. Pat. No. 97,316, granted to Andrew Rogers on Nov. 30, 1869; in U.S. Pat. No. 473,512, granted to John Laird on Apr. 26, 1892; and in U.S. Pat. No. D364,338, granted to Roger Cline on Nov. 21, 1995, such snow guards are typically one-piece members that do not lend themselves to flexibility in utilization. 
     Accordingly, it would be desirable to provide a snow guard structure for shingled roofs that will replicate the advantages of snow guards on raised seam roofs and provide flexibility in use and in aesthetic selection. 
     SUMMARY OF THE INVENTION 
     It is an object of this invention to overcome the disadvantages of the prior art by providing a snow guard for a shingled roof in which the snow guard attachment is replaceable. 
     It is another object of this invention to provide a mounting bracket for mounting devices to an attachment strap that is used to affix a snow guard to a shingled roof structure. 
     It is a feature of this invention that the mounting bracket detachably mounts to the attachment strap by fasteners. 
     It is still another object of this invention to provide a mounting bracket that has a universal nature in accommodating a variety of sizes and shapes of snow guard attachments. 
     It is further feature of this invention that the implement mounting system is formed with a wedge-shaped opening and a fastener that locks an implement to the top of the mounting bracket. 
     It is a still another advantage of this invention that the implement or device to be mounted on top of the mounting bracket can be quickly and easily replaced. 
     It is a further object of this invention to provide a snow guard device that can be attached to a mounting bracket to retain snow on the surface of an inclined shingled roof structure. 
     It is still a further object of this invention to provide a snow guard for a shingled roof structure, which is durable in construction, inexpensive of manufacture, carefree of maintenance, facile in assemblage, and simple and effective in use. 
     These and other objects, features and advantages are accomplished according to the instant invention by providing a snow guard for a shingled roof in which the flat attachment strap positionable between layers of shingles has mounted thereon a detachable mounting bracket that projects upwardly from the attachment strap. The body portion of the mounting bracket has a wedge-shaped receptacle on the top surface to mount devices such at a snow guard attachment, which can be locked into place on the mounting bracket by a threaded fastener that passes through the mounting bracket into the base of the snow guard attachment. The snow guard attachment can be easily replaced with aesthetically different snow guard members or a snow fence that spans across several aligned mounting brackets. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The advantages of this invention will become apparent upon consideration of the following detailed disclosure of the invention, especially when taken in conjunction with the accompanying drawings wherein: 
         FIG. 1  is a perspective view of a snow guard incorporating the principles of the instant invention, the assembled snow guard apparatus includes a mounting bracket detachably fastened to the attachment strap with a removable eagle-shaped snow guard attachment mounted on the mounting bracket; 
         FIG. 2  is a rear elevational view of the mounting bracket depicted in  FIG. 1  with the fastener openings being shown in phantom; 
         FIG. 3  is a right side elevational view of the mounting bracket of  FIG. 2 ; 
         FIG. 4  is a bottom plan view of the mounting bracket of  FIG. 2 ; 
         FIG. 5  is a plan view of the attachment strap; 
         FIG. 6  is an elevational view of the snow guard attachment for mounting in the mounting receptacle of the mounting bracket; 
         FIG. 7  is a bottom plan view of the snow guard attachment of  FIG. 6 ; 
         FIG. 8  is a side elevational view of the snow guard attachment orthogonal to the view of  FIG. 6  and corresponding to lines  8 — 8  of  FIG. 9 ; and 
         FIG. 9  is a rear elevational view of the snow guard attachment looking perpendicularly to the body portion of the attachment, corresponding to lines  9 — 9  of  FIG. 8 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to  FIGS. 1–5 , a snow guard structure for use with shingled roofs, incorporating the principles of the instant invention, can best be seen. The primary attachment structure for the snow guard assembly  10  is an attachment strap  12  having holes  13  extending therethrough to permit the attachment strap  12  to be positioned between layers of shingles (not shown) and nailed to the underlying roof structure with nails (not shown) passing through the holes  13  to affix the attachment strap  12  to the shingled roof (not shown) in a manner that will not incur leaks through the roofing structure. 
     The attachment strap  12 , as is best seen in  FIG. 5 , is also provided with a pair of fastener openings  14  through which corresponding fasteners  15  can pass to threadably engage corresponding openings  22  within the mounting bracket  20 . Thus, the fasteners  15  detachable connect the mounting bracket  20  to the attachment strap  12  at one end thereof which would protrude from between the layers of shingles (not shown). The top surface  21  of the mounting bracket  20  is formed with an attachment receptacle  25  for mounting implements and/or attachments to the mounting bracket  20 . The attachment receptacle  25  is formed as a relief depression into the top surface  21 . The depression preferably extends across the entire top surface  21  of the mounting bracket  20  and has a first generally vertical edge  27  and an inwardly beveled wedging edge  28  opposite to the vertical edge  27 . The attachment receptacle  25  is operable to receive an attachment formed with a correspondingly matched base member  31 , as will be described in greater detail below. 
     The mounting bracket  20  is also formed with a fastener opening  29  that passes through the mounting bracket from top to bottom to align with a corresponding opening  19  in the attachment strap  12 . A long fastener  40  can pass through the attachment strap  12  and through the entire body of the mounting bracket  20  to engage a threaded opening  34  in the base  31  of the snow guard attachment  30  to detachably fasten the snow guard attachment  30  to the mounting bracket. By trapping a correspondingly shaped edge of the base  31  of the snow guard attachment underneath the wedging edge  28  and locking the base  31  to the attachment receptacle  25 , the snow guard attachment  30  is securely fixed as part of the snow guard assembly  10 . 
     A representative snow guard attachment  30  in the form of an eagle-shaped snow retention member  35  can be seen in  FIGS. 6–9 . The snow retention member  35  is formed in a transversely extending body  37  having a shape that extends laterally of the mounting bracket  20  and projects downwardly to come into close proximity or into engagement with the flat surface (not shown) of the roof to either side of the mounting bracket  20  to which the snow retention member  35  is to be mounted. In the configuration depicted in  FIGS. 6–9 , the transversely extending body  37  of the snow retention member  35  is shaped like a bird whose wings  38  extend downwardly. The body  37  is integrally formed with the base member  31  that is configured to be received within the attachment receptacle  25  on the top surface  21  of the mounting bracket  20 . The base member  31  is formed with a first generally perpendicular edge  32  that corresponds to the vertical edge  27  of the attachment receptacle  25  on the top surface  21  of the mounting bracket  20 , and with a beveled edge  33  that corresponds to the wedging edge  28 . 
     The body  37  is angled preferably at about 60 degrees to the base member  31 , as is best seen in  FIG. 8 , to orient the body  37  in a more perpendicular orientation with respect to the plane of the roof when attached to a mounting bracket  20 . If, for example, the roof was pitched at a 30 degree angle, the body  37  would then be literally perpendicular to the plane of the roof to provide resistance to the movement of snow downwardly over the surface of the roof. To resist the bending forces that are exerted on the body  37  of the snow retention member  35 , integral braces  38  extend fore-and-aft between the body  37  and the base member  21 . The brace  38  on the uphill side of the snow retention member  35  will receive the threaded passage  34 . 
     One skilled in the art will readily recognize that many different attachments can be formed with a base member  31  that can be received by the attachment receptacle  25 . Snow guards  35  can be formed in many different shapes and sizes for mounting on the mounting bracket  20 . A snow fence (not shown), which would be equipped with a plurality of base members  31  that would be received with a corresponding number of mounting brackets  20  mounted generally parallel to the peak of the roof structure, would be an alternative example of a snow guard. Other attachments can be antennas, display signs, air conditioning units, ladders and walk ways. All such configured attachments can be quickly and easily attached to the mounting bracket by receiving the base member into the attachment receptacle  25  and connecting the locking fastener  40  to fix the base member  31  to the top surface  21  of the mounting bracket  20 . 
     For assembly, the mounting bracket  20  is affixed to the attachment receptacle  25  by inserting the fasteners  15  through the holes  14  in the attachment strap  12  and into engagement with the threaded openings  22  in the mounting bracket  20 . The snow retention member  35  is then attached to the mounting bracket  20  by slipping the base member  31  into the attachment receptacle  25  on the top surface  21  of the mounting bracket  20  with the beveled edge  33  positioned underneath the wedging edge  28 . The locking fastener  40  is then inserted through the opening  19  in the attachment strap and then through the opening  29  through the mounting bracket  20  into the threaded passage  34  in the base member  31  of the snow retention member  35 , thus fixing the base member  31  to the top surface  21  of the mounting bracket  20 . One skilled in the art will readily recognize that a different form of attachment could utilize a locking fastener  40  that is inserted through the attachment from above the mounting bracket  20  and engaged into the aperture  34  which would be threaded to engage the locking fastener  40 . In such a configuration, however, the locking fastener  40  would not be protected from beneath the top surface  12  of the mounting bracket  20 . 
     The attachment strap  12  can then be inserted between layers of shingles and nailed into position with roofing nails, or the like, being inserted through the nail holes  13  in the attachment strap  12  and into the roof structure (not shown). The lower end of the snow guard assembly  10 , including the mounting bracket  20  with the snow retention member  35  mounted thereon is left projecting out of the layered shingles for engagement with the snow accumulated on the roof to restrict movement thereof downwardly to the ground. 
     It will be understood that changes in the details, materials, steps and arrangements of parts which have been described and illustrated to explain the nature of the invention will occur to and may be made by those skilled in the art upon a reading of this disclosure within the principles and scope of the invention. The foregoing description illustrates the preferred embodiment of the invention; however, concepts, as based upon the description, may be employed in other embodiments without departing from the scope of the invention.