Abstract:
An expandable tree-shaped device is formed from a sheet of material which includes a central apex and a plurality of spaced apart spiral strips extending therefrom, with the spiral strips being substantially coaxial to the central apex and to one another. The central apex and the spiral strips, in the operative position, are positioned in a vertically spaced, tiered array, with the central apex at an uppermost position such that the tiered array is configured to have a generally conical tree-shape. A plurality of connecting segments join each spiral strip or tier of the array to a next adjacent spiral strip or tier of the array to form a unitary structure. The width of each spiral strip increases proportionately with the increase in radial distance from the central point.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to an artificial tree, such as an artificial coniferous or Christmas tree, which is easy to assemble and disassemble, and when disassembled occupies a small amount of space which facilitates storage. 
   Artificial trees, such as artificial evergreens or Christmas trees, have been known for many years and have been formed in various manners. In particular, such artificial trees are known to be formed from a number of natural and synthetic materials to provide individual branches, which may be removably mounted to a central pole resembling a tree trunk. These known trees are thus disassembled by removing the branches or collapsed by folding the branches. However, such known trees are often difficult to assemble and disassemble, or assembly and disassembly is time consuming, and/or the disassembled condition of the tree occupies a large amount of space making storage difficult and costly. 
   Artificial trees have also been designed, such as disclosed in U.S. Pat. No. 6,139,168, that incorporate three spaced-apart spiral strips having connecting strips at spaced-apart intervals to interconnect the spiral strips and form a unitary structure. However, such known artificial trees often require additional support structure, such as a central pole or trunk, to assemble and display the tree. Additionally, although the assembled structures give a tree-like impression, the uniform dimensions of the spirals and placement of connectors does not create a “natural” appearance of a tree. 
   In nature, growth occurs in geometric proportionate ways, or patterns. There has been a substantial amount of research directed toward the natural phenomenon associated with growth patterns. The natural growth patterns have been associated or interconnected with mathematical expressions or constants, such as the Fibonacci Sequence (0,1,1,2,3,5,8,13 . . . ) and the Golden Mean (1.618 . . . ), which in turn is related mathematically to geometries such as pentagrams and the Golden Rectangle (W =1, L =1.618 . . . ) or Golden Triangle. These relationships of natural growth are ultimately expressed in the spiral shape. This relationship of the spiral to natural growth is easily seen in the shape of the nautilus shell, the arrangement of sunflower seeds in the sunflower, in the bracts of pinecones and curls of ferns, among other various natural phenomena. In natural growth, there is no simpler law than this, namely that it shall widen and lengthen in the same unvarying proportions. The shell, like the creature within it, grows in size but does not change its shape; and the existence of this constant relativity of growth, or constant similarity of form is the essence of the spiral. A spiral is a curve on a plane that winds around a fixed center point at a continuously increasing or decreasing distance from the point. 
   Botanists have shown that plants grow from a single tiny group of cells right at the tip of any growing plant, called the meristem. There is a separate meristem at the end of each branch or twig where new cells are formed. Once formed, they grow in size, but new cells are only formed at such growing points. Cells earlier down the stem expand and so the growing point rises. Thus the lower (older) branches of a plant, such as a tree, are larger than the higher (newer) branches. 
   The prior art expandable trees do not follow the principle of geometric growth and therefore, their lower branches (portion of the spiraling strips nearer the lower end), which are of equal width to the higher branches (portion of the spiraling strip nearer the central axis) do not assume a “natural” tree-like appearance. 
   It is an object of the present invention to provide an artificial tree, which may symbolically represent a coniferous or Christmas tree and which is quickly and easily assembled to assume a “natural” appearance of natural growth. 
   SUMMARY OF THE INVENTION 
   Accordingly, the present invention relates to a relatively problem-free, readily assembled artificial tree such as a Christmas tree. The artificial tree of the present invention can be quickly assembled, often in as little time as a few moments, and can be equally quickly disassembled. Furthermore, upon disassembly, the artificial tree of the present invention occupies a relatively compact space, which is significantly smaller than previously known artificial trees. Thus, the artificial tree of the present invention is also easy to store. 
   In accordance with the present invention, an expandable tree element or tree-shaped device is formed from a unitary sheet of material which includes a central apex and a plurality of spaced apart spiral strips extending therefrom, with the spiral strips being substantially coaxial to the central apex and to one another. The central apex and the spiral strips, in the operative position, are positioned in a vertically spaced, tiered array, with the central apex at an uppermost position such that the tiered array is configured to have a generally conical tree-shape. A plurality of connecting segments join each spiral strip or tier of the array to a next adjacent spiral strip or tier of the array to form a unitary structure. The width of each spiral strip increases proportionately with the increase in radial distance from the central point. Optionally, the width and/or the length of the connecting segments may also increase proportionately with the radial distance from the center point. The plurality of spaced apart spiral strips are defined by forming a plurality of slit arrays in the sheet of material. Each slit array comprises a plurality of radially spaced, discontinuous, annularly overlapping slits. The positioning of the slits determines the shape and dimensions of the spiral strips and connecting segments. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other features and advantages of the present invention will become apparent from the following description of the preferred embodiments, given as non-limiting examples, with reference to the accompanying drawings, in which: 
       FIG. 1  is a front perspective view of an artificial tree according to a first embodiment of the present invention; 
       FIG. 2  is a top plan view of the first embodiment of the present invention in a lay-flat presentation; 
       FIG. 3  is an enlarged, cut-away top plan view of a portion of the first embodiment illustrated in  FIG. 2 ; 
       FIG. 4  is a top plan view of a material blank depicting the design layout for forming an artificial tree in accordance with the present invention; 
       FIG. 5  is a front perspective view of an artificial tree formed from a material including score lines between connecting segments and spiral strips. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring to  FIGS. 1-4 , an artificial tree according to the present invention, generally identified by the numeral  10 , includes a base member or sheet  12  from which the tree is formed. Reference numerals will remain constant for like elements throughout the figures.  FIG. 2  illustrates base sheet  12  in a lay-flat position. The base member or sheet  12  includes a central apex or point  14 , which defines a generally central position of the sheet  12 , and ultimately a top of the tree  10 . The central point  14  preferably includes a means or fastening element for suspending the central point  14  in a vertically elevated position, such as an aperture  16  which is operable to receive a string or other suitable means for suspending the tree  10  from an elevated structure. By suspending the tree  10  from an elevated position, the tree  10  is configured by gravity in its expanded, tree-like position as shown in FIG.  1 . 
   The tree  10  is provided with a plurality of spaced apart, continuous spiral strips  18  that “grow” or extend from the central point  14 . In a preferred embodiment, such as that shown in  FIGS. 1-4 , the tree  10  includes five (5) spirals  18   a-e  that grow or extend from the central point  14 . As best shown in  FIGS. 2-4 , the sheet  12  is provided with a plurality of spiral slit arrays  20  with each slit array  20  comprising a plurality of radially spaced, discontinuous, annularly overlapping slits  21  that define the continuous spiral strips  18   a-e . The preferred embodiment includes five (5) slit arrays  20   a- e to form the five (5) spiral strips  18   a-e  having ends  19   a-e . The slits  21  that form each slit array  20  may be straight, although curvilinear slits are preferred as shown in  FIGS. 2-4 . As illustrated in  FIG. 3 , each slit array  20  includes a first slit  21   a  including a first end  23   a  and second end  23   b . First end  23   a  is spaced from the central point  14  and the first slit  21   a  extends outwardly in a curvilinear fashion such that second end  23   b  is spaced a greater distance from the central point  14  than the first end  23   a  and terminates in a different annular position than the first end  23   a . A second slit  21   b  of each array is spaced radially outward of the second end  23   b  and continues in the proportionately outward growth pattern as established by the first slit  21   a , but in a partially annularly overlapping arrangement. In the preferred embodiment, the amount of annular overlap increases proportionately with the increase in width of spiral strips as discussed below. Each slit array  20   a-e  is annularly offset from adjacent slit arrays at equal intervals around the center point  14  and follow the same growth pattern. 
   In order to give the tree  10  a more “natural” appearance, the width of each of the continuous spiral strips  18  continuously increases proportionately with the radial distance from the central point  14 . In other words, the width of a spiral strip is greater than the width of an inner next adjacent spiral strip, measured along the same radial line from the center point  14 , and is less than the width of an outer next adjacent spiral strip measured along the same radial line. 
   The tree  10  includes a plurality of connecting segments  22 , which form continuous bridges between adjacent spiral strips  18 . When the tree  10  is expanded vertically, the connecting segments  22  interconnect the plurality of spiral strips in a unitary structure. The connecting segments  22  are formed by the radial spacing and annular overlapping of slits  21  in each slit array  20 . The particular number of slits  21  used to define each slit array  20  may be selected to be any number, but it should be noted that the length of the slits  21  and the amount of annular overlap between the slits  21  in each array  20  determines the length of the connecting segment  22  and hence the spacing between the spiral strips  18   a-e  as seen in FIG.  1 . In order to provide a more “natural” appearance of the tree  10 , the annular overlap of the slits  21  in each array  20  may be increased proportionately as the radial distance from the central point  14  increases, to increase the length of the connecting segments  22 . Thus, the vertical spacing between spiral strips  18 , when the tree  10  is configured in its expanded form, increases the further the spiral strip  18  extends from the central point  14 . This ensures that the lower “branches” of the tree  10  have greater spacing than the upper “branches” as occurs in nature. Also, the radial spacing of the slits  21  within the same array  20  may increase proportionately as with the spiral strips  18  discussed above. This provides for an increasing width of the connecting segments  22  proportionate to the increasing width of the spiral strips  18   a-e.    
   The base sheet  12  may be formed from any material with suitable structural characteristics that allow for expansion of the tree  10 , such as paper, plastics, chipboard, cardboard, metals and composites or laminates of the foregoing, so long as the material is able to be cut, scored, creased and/or bent. Preferably, the sheet  12  is a plastic material. Plastic materials are preferred for their wide variety of structural and light absorbing/reflecting characteristics, as well as their economic qualities. If more rigid materials are used, such as chipboard or metal sheeting, it may be necessary to bend, crease, score or otherwise provide a line of weakness in portions of the sheet  12  such that the material is induced to pivot at predetermined locations when the tree  10  is hung by the central point  14 . For example, if copper sheeting is used, it may be necessary to provide a weakened area or score  24   a  ( FIG. 2 ) in the material extending radially between an outward end of each slit to the outwardly next adjacent slit, and a score  24   b  extending radially between the inner slit and the outwardly next adjacent slit. Thus, the ends of connecting segment  22   a  are both scored such that during the raising of the tree  10 , the gravitational forces are directed to act on the predetermined scores, causing the copper sheeting to pivot or bend in the predetermined position and reducing the risk of unwanted creasing within the length connecting segment  22   a.    
   The material forming the sheet  12  is preferably die-cut to form the radially spaced, annularly overlapping slits  21 , such as shown in FIG.  3 . However, the slits  21  may be formed in any known manner, such as by cutting, sawing, or by the use of a laser cutting apparatus. Preferably, the aperture  16  is also cut at the central point  14 . The aperture  16  allows for the easy attachment of an elongate flexible member, such as a wire or string, or other structure that allows the tree  10  to be hung and thereby expand the tree  10 . If an aperture is not provided, the user may simply thread wire or string through the five innermost slits  21  to suitably secure the tree  10 . Optionally, the tree  10  may be draped over a central pole (not shown) that supports the tree  10  at the central point  14 . 
   During the die-cutting or forming step, a plurality of mounting apertures  26  may be provided within each spiral strip  18   a-e  to provide a point of attachment and suspension of lighting strips or traditional tree ornaments. Optionally, the surface of the sheet  12  may be provided with ornamentation in the form of printed graphics and/or topography. For example, a plastic sheet may be vacuum formed to provide a pine needle-like surface that resembles a natural tree and which adds additional light scattering characteristics to the tree  10 . 
   When hung from or supported at the central point  14 , the force of gravity operates to expand the tree  10 . The connecting segments  22  provide for a predetermined spacing between each spiral strip  18  to form a unitary coniferous, or Christmas tree-like device. Preferably, the tree  10  is suspended completely above the floor or other surface such that the tree  10  may expand and contract, or rise and fall, as well as rotate about the central point  14  due to natural or artificial air circulation. Optionally, the spiral strip ends  19   a-e  may be secured to a surface or otherwise weighted to prevent such movement. The tree  10  may be illuminated with natural or artificial light sources from above, below, on (as discussed above) or within. The choice of material for the sheet  12  will determine from which source and from which direction the tree  10  is best illuminated. 
   While the above-mentioned features and advantages of this invention and the manner of obtaining them may be apparent to understand the method of producing an artificial tree according to the present invention, the inventive method of manufacturing an artificial tree, itself, may best be understood by reference to the following description taken in conjunction with the above identified features. 
   Referring to  FIG. 4  of the drawings, a blank of material  12   a  from which the base sheet  12  is cut is shown. The blank  12   a  which is used to form the tree or tree-shaped device of the present invention may comprise any desirable shape, such as a thin rectangular sheet material, preferably plastic. The base sheet  12  can have any suitable size, and in a preferred embodiment, provides for a circular disc having a diameter of about  48  inches to be cut from the base sheet. 
   As can be seen from  FIG. 4 , the base sheet  12  includes a central point  14 , which is established to be the focal point from which the remaining parts are defined. Two sets of radial guidelines  35  and  37  are overlaid on the base sheet  32 . Each set of radial guidelines  35  and  37  includes five lines  35   a-e  and  37   a-e  respectively. Each of the lines  35   a-e  and  37   a-e  passes through and intersects at the center point  34 . The lines  35   a-e  and  37   a-e  are annularly offset an equal amount within each set of radial guidelines  35  and  37 , preferably thirty-six degrees. The two sets of radial guidelines  35  and  37  are, in turn, offset annularly, preferably five to ten degrees. The radial guidelines  35  and  37  determine the beginning and end of slits  21  provided in the sheet  12 . 
   As can be seen from  FIG. 4 , there are five (5) spiral slit arrays  20  extending from the center point  14 . One spiral slit array  20   a  is shown darker in  FIG. 4  for illustration purposes. Each spiral slit array  20  includes a number of curvilinear slits  21  made through the material of the blank  12   a . As best shown with respect to slit array  20   a , a first slit  21   a  begins on line  35   a  and extends in a generally curvilinear manner with its distance from the central point  14  increasing proportionately with the annular distance traveled. The first slit  21   a  terminates at line  37   c . A second slit  21   b  is spaced radially outwardly from the first slit  21   a  and extends from line  35   b  in a generally curvilinear manner and terminates at line  37   d . A third slit  21   c  is spaced radially outwardly from the second slit  21   b  and extends from line  35   c  in a generally curvilinear manner and terminates at line  37   e . This pattern continues until the spiral slit array  20   a  extends to the outer perimeter desired for the tree. Every slit  21  in a spiral slit array  20  is proportionately longer as the radial distance from the center point  14  increases. Preferably, the radial spacing between each slit  21  in the array  20  also increases as the radial distance from the center point  14  increases. An end slit  39  is provided between the outward end of the last slit  21  of each slit array  20  and the inner end of the last slit  21  of each inner next adjacent slit array  20  to fully separate the base sheet  12  from the blank  12   a.    
   The base sheet  12  is preferably die-cut according to the above design and provided with an aperture  16  or other suitable means that allows for the suspension of the tree, located at the central point  14 . A wire, string or other suitable means for suspending the tree is attached at the central point  14  and further attached to an elevated surface, e.g.: a ceiling beam, such that gravity acts to expand the tree to the configurations shown in  FIGS. 1 and 5 . 
   Accordingly, the artificial tree of the present invention as set forth above can be quickly assembled, often in as little time as just a few moments, by simply pulling the disc-shaped base member upwardly to form the vertically spaced tiered array, and hanging the tree from the central point  14 . Since the bottom portion of the tree  10  comprises radially larger members, gravity holds the tree in its extended position. When the tree is no longer needed for display, the tree can be readily disassembled by merely reversing the assembly operations. Furthermore, upon disassembly, it can be seen that due to the collapsibility of the base member into a generally sheet form, the disassembled artificial tree of the present invention occupies a relatively compact space. Thus, the artificial tree of the present invention is also easy to store. 
   Although the above invention has been described with particular means, materials and embodiments, it is to be understood that the invention is not limited to the particulars disclosed and extends to all equivalents within the scope of the claims.