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 
   The present invention relates to rain gutter and downspout systems, and in particular to such systems with principal components formed of flat, seamless material that may be distributed on a spool and cut to a desired length. 
   Rain gutter and downspout systems are widely employed on commercial and residential buildings to direct rainfall to a desired location, thereby preventing erosion and the other deleterious effects of uncontrolled water run-off from building roofs. The U.S. market for rain guttering systems is large, exceeding one billion dollars annually. Those rain gutter systems on the market today fall into one of three major classes: vinyl sectional, metal sectional, and seamless metal. A fourth method, currently only used to a very small extent in Canada, is fused (or “virtually seamless”) vinyl. 
   Vinyl sectional rain gutter systems are constructed from pre-formed sections of U-shaped plastic material, usually ten feet in length. Because no expensive, customized equipment is necessary for the installation of sectional vinyl pieces, this class of rain gutter systems is the preferred choice of do-it-yourself installers. Sectional systems, however, are time-consuming to install, as connectors are required at each point where the pre-formed sections are fitted together. These connectors are prone to leak or otherwise fail after the system has been in place for some time. The connectors also increase the cost of this type of guttering system. One connector costs approximately two-thirds as much as a ten-foot gutter section. The connectors must be designed to allow for the high degree of expansion and contraction that occurs in the vinyl material due to changes in temperature. Another important disadvantage of this type of system is that the connectors ruin the smooth, uninterrupted appearance of the gutters, and thus may negatively impact the appearance of the home or other building upon which the gutters are installed. Appearance is known to be an important factor in the selection of a guttering system, particularly with respect to homes and retail business establishments. 
   Another factor adding to the cost of sectional vinyl gutter systems is the required hangers and downspouts. In order to prevent sagging, vinyl sectional guttering systems require hangers to be installed from the building at approximately two-foot intervals along each gutter section. The price of hangers for a typical installation project will be more than double the price of the ten-foot gutter sections themselves. The increased cost is a result of forming the connectors and hangers from the more expensive injection-molding technique required. Extruded plastic is much less expensive than injection-molded plastic. The downspouts for such systems are pre-formed into rectangular tubes, generally ten feet in length, and each such length is generally priced at one and one-half to two times the price of a ten-foot, U-shaped gutter section. It may thus be seen that much of the cost of this type of guttering system is hidden in the auxiliary components necessary for the installation of the complete system. 
   Metal sectional rain gutter systems are, like the vinyl sectional systems, constructed of pre-form U-shaped sections, again generally of ten-foot lengths. The sections in most metal gutter systems are constructed from aluminum, due to its low cost, relatively light weight, and resistance to corrosion. Copper and stainless steel sections are other options, but due to the prohibitively high cost of these materials they are seldom used. Like the vinyl sectional systems, the metal sectional systems also suffer from a number of disadvantages. Aluminum is easily bent, and once a bend occurs it is difficult or impossible to fully restore without the damage being visible. Each of the aluminum guttering system components must be painted for purposes of appearance, and any chip or nick in the paint will be highly visible. The installation of such a system is time-consuming due to the necessary use of connectors, which, as in the case of vinyl sectional systems, significantly drive up the cost of these systems. Also as with the vinyl sectional systems, the connectors ruin the clean, neat appearance of the guttering system. 
   Metal seamless, or continuous, guttering systems are formed on-site from flat sheets of metal. The flat metal, typically aluminum, is pulled from a spool or roll, cut to the appropriate length, and then bent or formed into the proper U-like shape by the use of a special forming machine. The downspouts of this type of system are typically pre-formed into a rectangular cross-sectional shape. Because the gutters are cut to the desired length on-site, this type of system require no connectors along the length of the building roofline, and thus provide the neat appearance that sectional gutter systems lack. For this reason, metal seamless guttering is by far the most popular choice for home guttering in the United States. This class of guttering system is, however, far more expensive than sectional guttering because of the requirement of a professional installation crew and forming machine on-site. The forming machine necessary to install metal seamless guttering costs an estimated $12,000 to $20,000, placing it well out of reach of typical do-it-yourself installers. The machine also requires special training for proper and safe use, thus discouraging a rental market for the forming machines. Like sectional metal guttering systems, the components of this system are highly susceptible to bending and chipping of paint. 
   A newer product on the market is fused vinyl, or “virtually seamless” vinyl guttering. This product is sold exclusively to gutter installation specialists and is currently available only in Canada. Using this system, the vinyl sections are fused together on-site by means of a fusing machine operated by the gutter installation crew. The beaded seam is then trimmed or sanded. Although the seam is thus still visible, it is not as glaringly visible as the connectors of traditional sectional guttering. Like seamless metal guttering, this type of guttering system is expensive, and not available for do-it-yourself installers. The machine used to fuse the guttering material costs an estimated $6,000 to $10,000, and, like the forming machine used for metal seamless gutters, is not safe for use by untrained do-it-yourselfers. Although this machine has a lower cost than that of the forming machine used for seamless metal guttering, the installation process for fused vinyl takes roughly twice as long, which drives up labor costs associated with installation. The hangers used for this type of guttering system, like the hangers used for vinyl sectional guttering, require injection molding, and are required at about every two feet of guttering length. 
   It may be seen that each of the existing classes of guttering systems suffer from important disadvantages. What is desired then is a guttering system that provides the neat appearance of seamless guttering but that does not require specialized equipment to form the guttering pieces from a flat roll on site. In particular, such a guttering system would be highly desirable if such system were safe and otherwise appropriate for installation by do-it-yourself homeowners. 
   The prior art does contain an attempt to develop a seamless plastic material for a gutter-related application. U.S. Pat. No. 6,308,464 to Demartini teaches a downspout for use with a rain gutter that is formed from a flat plastic sheet disposed on a roll prior to construction. The necessary downspout length is cut from the roll, then the sheet is bent into the desired shape, which may be either a rectangular or oval cross-sectional configuration. Bending is facilitated in the rectangular configuration by longitudinal regions in the plastic sheet that comprise a more flexible plastic material than the material used to form the bulk of the sheet. Alternatively, the plastic material forming the sheet may be made thinner where the bends are to occur so that the material will be more flexible at these locations. 
   While Demartini &#39;464 teaches a downspout system formed using a plastic material that may be cut to a desired length, the system falls far short of a complete seamless guttering system, or even a gutter itself. Neither the rectangular nor oval configuration used for the downspout of Demartini &#39;464 could be used for gutters, since the rainwater would have no means of entering the gutter when deployed. No system for connecting the pieces of such a system are taught by Demartini &#39;464, since, due to the fact that Demartini &#39;464 is limited to the use of a downspout for an existing gutter system, no such connectors are required. In addition, Demartini&#39;s downspout has no mechanism to lock and hold the rectangular or oval shape along its length. This will allow the downspout to twist and bulge out of shape between points of anchorage to the wall of the building. Also, without locking mechanisms the downspout material will be wavy after being wound on a spool. What is desired then is a complete guttering system that is formed of a continuous flexible sheet, providing the advantages of such a system that are described herein. 
   SUMMARY OF THE INVENTION 
   The present invention is directed to a seamless gutter system that is formed of flat plastic material. The flat material is thinned along longitudinal strips in the plastic sheet, thereby allowing the material to be folded once it is cut to length. The folding system results in a generally U-shaped configuration for the gutter produced by this method. Optionally, a leaf guard may be placed onto the gutter, the leaf guard being formed from another plastic sheet, which may similarly be provided in a roll and cut to length. Tabs that are preferably integrally molded into the flat plastic material hold the “U” shape of the gutter, so that no reinforcement is required. A downspout may be formed of the same material as the gutter, with a downspout “top cap” closing the three sides of the U-shaped gutter to create a closed downspout piece. Corner connectors and optional hangers complete the system, all of which may be formed of vinyl or other plastic material for durability, ease of installation, and low cost. 
   It may be seen that such a system results in a guttering system that provides a neat, uninterrupted appearance similar to that of metal seamless guttering. The present invention, however, provides this neat appearance at a much lower cost, since no specialized forming machine is required at the job site. The need for trained forming machine operators is thus eliminated also, making the present invention ideally suited for do-it-yourself installation, as well as installation by professional gutter contractors. The rolls of material and other components of the system could preferably be available for purchase at a retail outlet, such as a home-improvement store, whereby the homeowner would need only to bring his or her home measurements to the store in order to purchase the necessary lengths of material and related components. In addition, it may be seen that the present invention would be desirable by building contractors as well; contractors currently must hire or train gutter installation specialists in order to install seamless metal guttering, but by employing the present invention could use their own general construction labor for the installation process, thereby lowering the costs associated with each project involving a gutter installation. In addition, independent gutter installation contractors can install seamless gutters without the requirement of an expensive bending or forming machine. 
   It is therefore an object of the present invention to provide for a seamless guttering system formed of a plastic or other flexible material. 
   It is a further object of the present invention to provide for a guttering system that is inexpensive to purchase and install. 
   It is also an object of the present invention to provide for a guttering system that may be installed by a do-it-yourself homeowner or other untrained person or persons. 
   It is also an object of the present invention to provide for seamless guttering without the requirement of an expensive bending or forming machine. 
   It is also an object of the present invention to provide a seamless gutter, which combined with a seamless top cap that can be snapped onto the gutter, can be converted into a seamless downspout. 
   It is also an object of the present invention to provide for a guttering system that has a clean, attractive appearance. 
   These and other features, objects and advantages of the present invention will become better understood from a consideration of the following detailed description of the preferred embodiments and appended claims in conjunction with the drawings as described following: 

   
     DRAWINGS 
       FIG. 1A  is a perspective view of a flat gutter section according to a preferred embodiment of the present invention. 
       FIG. 1B  is a side elevational view in cut-away of a flat gutter section with non-uniform wall thickness according to an alternative embodiment of the present invention. 
       FIG. 2  is a perspective view of a folded and deployed gutter section according to a preferred embodiment of the present invention. 
       FIG. 3  is a perspective view of a hanger section according to a preferred embodiment of the present invention. 
       FIG. 4  is a perspective view of a leaf guard section according to a preferred embodiment of the present invention. 
       FIG. 5A  is a side elevational view in cut-away of a leaf guard section according to an alternative embodiment of the present invention. 
       FIG. 5B  is a front elevational view of a leaf guard section according to an alternative embodiment of the present invention. 
       FIG. 6  is a perspective view of a corner connector according to a preferred embodiment of the present invention. 
       FIG. 7  is a perspective view of an assembled downspout connector, as attached to a gutter segment after a hole to receive the connector has been cut into the gutter by the installer, according to a preferred embodiment of the present invention. 
       FIG. 8A  is a perspective view of a downspout connector flange according to a preferred embodiment of the present invention. 
       FIG. 8B  is a perspective view of an expanding downspout connector according to a preferred embodiment of the present invention. 
       FIG. 9  is a perspective view of a downspout “conversion cap” wall section according to a preferred embodiment of the present invention. 
       FIG. 10  is a perspective view of a circular downspout connector flange according to an alternative embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   With reference to  FIGS. 1A and 2 , a section of the U-shaped gutter material used in a guttering system according to a preferred embodiment of the present invention may now be described. Guttering section  10  is preferably formed of vinyl, but may be formed of other flexible materials. The vinyl is preferably formed by means of the extrusion method, but other methods may be used in alternative embodiments, such as injection molding. Guttering section  10  is molded with a series of thinned strips and interlocking tabs that are adaptable, as will be described, to hold the gutter into a “U” shape when installed. Each of these features are preferably integrally molded with the material of guttering section  10  as shown in  FIG. 1A . Specifically, two longitudinal strips of thinner material  12  in guttering section  10 , shown in  FIG. 1A , appear at the location where bends must occur in order to form the “U” shape depicted in  FIG. 2 . These thinned strips force the guttering section  10  to bend first at thinned strips  12  when pressure is applied upward at each edge during the forming step prior to installation. An inner tab  14  and an outer tab  16  appear at each of the inner and outer edges of each thinned strip  12 , respectively. It may be noted that this tab configuration could well be reversed in alternative embodiments. In further embodiments, one of the tabs may comprise a slot to receive a protrusion on the opposite tab. The term “tab,” as used herein, is intended to encompass any means of locking the gutter together in the U-shaped position. When deployed in the preferred embodiment as illustrated in  FIG. 2 , outer tab  16  fits over inner tab  14 , with the extending lip of outer tab  16  locking in place under the lip of inner tab  14 . A frictional fit is thereby formed between each inner tab  14  and outer tab  16  to hold the “U” shape of the deployed guttering section  10 . Again it may be noted that, in alternative embodiments, various other types of locking tabs, with or without matching protrusions, lips, or receiving slots, may be employed within the scope of the present invention. 
   In the preferred embodiment, spaces, slits, or gaps (not shown in  FIG. 1A ) may be placed periodically within the length of inner tabs  14  and outer tabs  16 . The purpose of the spacing is to enable to product to be more easily spooled without stretching or bending due to the resistance to lateral bending of the thick tabs. The spaces or gaps provided in inner tabs  14  are preferably offset from those of outer tabs  16 ; in this way, the slits will not compromise the rigidity of the resulting gutter system when gutter section  10  is in the deployed “U” shape with inner tabs  14  and outer tabs  16  locked together. Similar spaces or gaps may be provided for this purpose in hanger tabs  18  (the purpose of which will be described below). 
   While in the preferred embodiment the thickness of the wall of gutter section  10  is uniform, as shown in  FIG. 1A , the thickness may be varied in alternative embodiments to improve the strength of the resulting gutter system. For example, those portions of gutter section  10  that corresponds to the gutter sides when assembled may be progressively thicker towards the bottom of the gutter, thereby increasing the rigidity of the system when locked into the deployed “U” shape. The result is thickened side walls  11 , as depicted in  FIG. 1B . Since the maintenance of a uniform total material thickness across the width of the material simplifies the process of producing plastic products by means of extrusion, it is preferred to construct such a wall with a cavity  13  within the thickened portion, whereby the total material thickness remains laterally uniform. 
   Referring now to  FIG. 3  in conjunction with  FIGS. 1A and 2 , a hanger and mounting method may be described with respect to the preferred embodiment of the present invention. Hanger section  22  and the tabs extending from it are preferably molded of a single, integral piece in the same general manner as described above with respect to gutter section  10 . Hanger section  22  is adapted to receive and hold gutter section  10  in place by means of gutter male tabs  18  and hanger female tabs  24 . As may be seen by comparison of  FIGS. 2 and 3 , the deployed gutter section  10  may be fitted to hanger section  22  by applying pressure behind hanger male tabs  18  to cause them to snap into the space created by each pair of hanger female tabs  24 . The lip on these tabs causes gutter section  10  to be securely held in place with respect to hanger section  22 . The gutter male tabs will preferably fit securely, but somewhat loosely, within the hanger female tabs, to allow the gutter to slide along the hanger as it expands and contracts. Various other types of tabs may be used in alternative embodiments. 
   In the preferred embodiment, hanger section  22  is mounted to the eave or otherwise just below the roof line of the building upon which the preferred embodiment is to be installed. This mounting may be by screws, staples, or other means. Holes (not shown) may optionally be periodically placed along the length of hanger section  22  for this purpose. 
   Gutter sections  10  and matching hanger sections  22  are cut to length for use based on the length of each section needed for the particular application. A homeowner, builder, or contractor could thus measure the dimensions of the roof perimeter of the home for which guttering is desired, and bring those measurements to a home improvement store or other vendor that makes available the preferred embodiment for purchase. The gutter section  10  material is preferably kept on a roll or spool, and can thus be unwound and cut to the length indicated by the customer&#39;s dimensions. In this way, no connectors are needed during long runs of the guttering material along straight roofing lines, thereby presenting a neat appearance and avoiding the cost of purchasing connectors for this purpose. 
   In alternative embodiments, hanger sections  22  may be omitted from the system as described above, and gutter sections  22  may be connected directly to the building eaves or otherwise just below the roof line. Holes (not shown in  FIG. 1A ) may be optionally included in the side of gutter section  10  in the area where male tabs  18  are shown in  FIGS. 1 and 2  for the purpose of receiving screws or other hanging hardware. If this alternate embodiment is used,  FIG. 1A  cap connector  20  will be a female connector rather than a male connector. In addition,  FIG. 4  leaf guard cap section  26  and  FIG. 9  downspout conversion cap section  44  will be male connectors rather than female. 
   Referring now to  FIG. 4  in conjunction with  FIGS. 1A and 2 , a leaf guard “cap” section  26  for the preferred embodiment of the invention may be described. Leaf guard section  26  is an optional attachment to gutter section  10 . In the preferred embodiment, screen  28  forms an integral part of leaf guard section  26 , and like gutter sections  10  and hanger sections  22  it is provided on a roll and cut to length prior to use. In the preferred embodiment, female leaf guard tabs  30  on leaf guard section  26  are adapted to receive male leaf guard tabs  20  on gutter section  10  for the purpose of locking leaf guard section  26  in place. The form of screen  28  may be of any of various types designed to prevent the passage of debris but allow water to flow through. Screen  28  may comprise, for example, a series of slots or holes across the upper surface of leaf guard section  26 , or overlapping or interlocking mesh creating passages between individual fibers or strands. 
   In one set of alternative embodiments, screen  28  of leaf guard section  26  may be replaced with solid section  32  as depicted in  FIGS. 5A and 5B . Slots  34  positioned underneath the lip extend from solid section  32  to receive water while blocking debris from entering the gutter. Water flows across the top of solid section  32 , around the lip, and through slots  34  into gutter section  10  as a result of surface tension. The width of slots  34 , and the distance between successive slots  34  in leaf guard section  26 , may vary in various alternative embodiments. 
   A corner connector  36  according to a preferred embodiment of the present invention is depicted in  FIG. 6 . A rigid corner section  38  forms a U-shaped trough with a general shape that is congruent with that of an assembled gutter section  10 , except that it includes a right angle to accommodate corners of the building to which the guttering system is attached. Corner connector  36  is attached to gutter sections  10  at expanding corner sections  40 . Expanding corner sections  40  may be integrally molded with rigid corner section  38 , or assembled with rigid corner section  38  in any secure manner as known in the art, but in the preferred embodiment the assembly is performed either by gluing or heat welding. The accordion-like structure of expanding corner sections  40  allows the assembled guttering system to expand and contract due to changes in temperature during the year, without damaging the system or causing its connection with the building to loosen. In the preferred embodiment, expanding corner sections  40  are each connected to a gutter section  10  by overlapping the parts and applying a glue appropriate to the material used for these parts. In an alternative embodiment, the connection is formed by configuring expansion edge  41  of each expanding corner section  40  as a slot or groove, whereby the gutter edge will act a matching tab or tongue at the end of gutter section  10 , thereby forming a tongue-and-groove type connection. 
   Referring now to  FIGS. 2 and 9 , the downspout conversion “cap” portion of a preferred embodiment of the present invention may be described. A downspout for the guttering system is formed by the assembly of a gutter section  10 , as depicted in its deployed U-shaped configuration in  FIG. 2 , and downspout section  42 , as shown in  FIG. 9 . Like gutter sections  10 , hanger sections  22 , and leaf guard sections  26 , downspout section  42  is preferably provided on a roll and cut to length prior to use. A corresponding length of gutter section  10  is also cut to form the downspout. In the preferred embodiment, female downspout tabs  44  on downspout section  42  are adapted to receive male cap tabs  20  on gutter section  10  for the purpose of locking downspout section  42  in place. The result is a four-sided pipe that is closed on all four sides. Alternative connection means as described with respect to gutter section  10  and leaf guard section  26  may also be employed in alternative embodiments. 
   Referring now to  FIGS. 7 ,  8 A, and  8 B, a downspout connection system for the preferred embodiment of the present invention may be described. The downspout connector of  FIG. 7  is comprised of two components, a flange  46 , shown in  FIG. 8A , and an expanding/flexing downspout connector  50 , shown in  FIG. 8B . Flange  46  includes a lip  48  that is sized to fit within the bottom portion of a deployed gutter section  10 . Flange  46  is further sized to fit within a hole that must be cut within the bottom portion of deployed gutter section  10 , such that flange  46  is inserted from the top of gutter section  10 , lip  48  rests on the top of the bottom portion of gutter section  10 , and the remainder of flange  46  extends downwardly below gutter section  10 . Since lip  48  has a greater circumference than the hole, lip  48  prevents flange  46  from passing entirely through the hole. Latitudinal lines of thinner material (not shown in  FIGS. 1 and 2 ) may be molded into gutter section  10  extending between longitudinal thinned sections  12  at periodic intervals, to facilitate the cutting of a properly sized hole in the bottom of gutter section  10  at the location where the downspout is desired. 
   Once flange  46  is in place, expanding/flexing downspout connector edge  51  is fitted over flange  46  from the bottom side of gutter section  10 , locking in place due to the friction between the parts. In alternative embodiments, scaling or tabs may be used on one or both of flange  46  and expanding/flexing downspout connector edge  51  to improve the shear strength of the friction fit between the parts. In other alternative embodiments, various connectors as are known in the art, such as screws and expanding brads, may be used to securely connect the parts. Expanding downspout connector  50  is designed to move laterally and longitudinally in accordion-like fashion in order to allow for the expansion and contraction of the guttering system components due to changes in temperature during the year. The expanding/flexing downspout connector  50  allows for vertical (longitudinal) expansion of the downspout, while at the same time allows flexing of the connector to compensate for the longitudinal movement of the gutter along the hanger as it contracts and expands, while the downspout is held in a fixed position against the side of the building. The downspout connector edge  49  can be glued to the edge of the downspout itself. Alternatively, the connector edge  49  can be configured as a slot or groove, and the downspout edge will act as a tongue, in a tongue-and-groove type connection. 
     FIG. 10  depicts an alternative downspout connector in circular flange  52 . Like flange  46 , circular flange  52  is fitted through a hole in gutter section  10  from the top, and lip  54  fits on the bottom of the gutter. Lip  54  is glued to the inside of the gutter bottom and the portion that protrudes beneath the gutter is placed loosely inside the downspout. The protruding portion  55  is not connected to the downspout, which allows it to move within the open end of the downspout as the gutter moves longitudinally along the hanger as it contracts and expands. 
   It may be noted that certain components of the invention are generally described herein as having a “U” shape when deployed. As used herein, this means that the sides are generally raised with respect to the bottom to form a shape that is at least somewhat reminiscent of a letter “U.” In the case of gutter section  10  of the preferred embodiment, for example, this shape is desired because water is held and directed within the trough-like bottom portion of the “U,” thereby functioning to catch and direct water to the desired location. This does not necessarily mean, however, that the sides of the component described as having a “U” shape are strictly perpendicular to the bottom of that component, or that the sides or bottom are necessarily flat or straight. 
   The material used in the construction of the preferred embodiment is vinyl. It may be noted, however, that other plastic materials may be used in alternative embodiments. Such materials may include, for example, polypropylene, or various laminates or cored materials that include plastic materials and non-plastic materials. In addition, the present invention, with relatively minor modifications, can be formed from relatively soft metals, such as aluminum or copper. The principal difference other than the material used in this embodiment is that a specially shaped cork or other cushioning material would preferably be wound on the spool or coil along with the metal. The purpose of the cushioning material is to keep the layers of metal from bearing on and bending the various tabs and channels of the gutter, hanger, leaf guard cap, and downspout conversion cap. 
   It may be noted that in an embodiment of the invention where plastic materials are used, the hanger, leaf guard cap, and downspout conversion cap parts are preferably formed of extruded plastic in order to limit costs. The corner connector should preferably be vacuum molded or injection molded for strength. Likewise, the downspout flange should be injected molded, and the expanding downspout connector is preferably blow molded. Each of these molding techniques are known in the art. 
   The present invention has been described with reference to certain preferred and alternative embodiments that are intended to be exemplary only and not limiting to the full scope of the present invention as set forth in the appended claims.

Summary:
A seamless guttering system formed of flat, seamless plastic is disclosed. The gutter material is thinned along longitudinal lines to be bent into a “U” shape, and includes connectors molded integrally with the flat material to lock the gutter into the proper form. The system also includes a seamless top piece that may be used to close the “U” shape into a box shape for the purpose of forming a downspout. A seamless hanger piece with connectors may be employed, or the gutters may be mounted directly to the building. Various seamless leaf guards may be employed in alternative embodiments. Flexible corner and downspout connectors complete the system.