Abstract:
A stand supports a burnable coil such as a mosquito coil. There is a base suitable to rest on a support surface which is positionable at least partially beneath the coil. There is also a retainer clip linked to the base that is simultaneously positionable along a top side of the coil near a central opening of the coil, through the opening, and along a bottom side of the coil adjacent the opening. Methods of using such stands and stand/coil assemblies are described.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    Not applicable 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH/DEVELOPMENT  
       [0002] Not applicable 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0003]    The present invention relates to stands for supporting burnable coils while they are burning. It appears to be particularly well suited for use with mosquito coils that are thin.  
           [0004]    Burnable coils, such as mosquito coils and incense coils, are designed to provide sustained vapor release. Because they burn slowly they are susceptible to being inadvertently extinguished, thereby rendering the coil ineffective. Inadvertent extinguishing can occur when too much heat is drawn from the coil by conduction to a contacting surface.  
           [0005]    To minimize the likelihood of inadvertent extinguishing, such burnable coils are typically impaled on a spaded post which holds all but their center portion up away from contact with a supporting surface. Such spades are designed to make only minimal contact with the coil, and then only adjacent the last portion of the coil to be burnt.  
           [0006]    However, some coils are made of a sufficiently flexible or fragile material that supporting them during burning merely from the center can lead to sagging of an outer portion of the coil, followed by inadvertent snuffing. Thus, the central spade is sometimes supplemented with additional raised points extending upward from a base bottom at other more radially remote positions under the coil. See e.g. U.S. Pat. Nos. 6,061,950 and 4,765,090. The disclosure of these patents and of all other publications referred to herein are incorporated by reference as if fully set forth herein.  
           [0007]    While such supports are of assistance in reducing the incidence of snuffing, they require a more complex base which can be more expensive to manufacture. This can be of greatest concern in countries with exceptionally low annual incomes. Such countries are often significant markets for mosquito coils.  
           [0008]    There have been attempts to design exceptionally thin mosquito coils that are mounted on a backing such as a round disk-shaped sheet of paper. Such coils have desirable burning characteristics. However, these coils have a tendency to sag if supported only from the center. Thus, a need exists for an inexpensive coil holder designed to better support this type of burnable coil.  
         BRIEF SUMMARY OF THE INVENTION  
         [0009]    In one aspect the invention provides a stand for supporting a burnable coil structure having an opening adjacent its center. The stand includes a base suitable to rest on a support surface. The base is positionable at least partially beneath the coil structure. There is also a retainer linked to the base that is simultaneously positionable along a top side of the coil structure near the opening of the coil structure, through the opening, and along a bottom side of the coil structure adjacent the opening. For purposes of this patent, the term “coil structure” shall be deemed to include both the coil itself and, where applicable, any backing that the coil may have.  
           [0010]    The retainer is preferably U-shaped with two essentially horizontal arms (e.g. in the form of a clip having arms suitable to make simultaneous contact against the top side and the bottom side of the coil structure). In one set of embodiments, the base and retainer are formed from a continuous piece of wire. For example, the base can be a closed path extending from a catch end to an intermediate point engaged by the catch end. There can also be a riser section of the wire that extends from the base to the retainer.  
           [0011]    The riser can either be positioned so as to pass outside and above the coil structure (so as to hang it from above), or be positioned directly under the coil structure so as to support the coil structure from underneath. This can advantageously be achieved by forming the retainer with a hairpin bend in it.  
           [0012]    In another set of embodiments the retainer is formed from a single piece of sheet material (e.g. sheet metal). One form of this can have a planar base portion and a planar tab extending upwardly from that base portion, the tab having a lateral slot with an open end forming the retainer. If desired, the base can also have angled corners extending upwardly to support the outer periphery of the coil structure from below.  
           [0013]    In another form the base and retainer are made of a sheet material, and the base includes a pair of planar feet joined to the retainer by an upwardly extending planar riser section. Alternatively, the sheet can form a convex surface to define the base which has extending therefrom a cut out tab to define the retainer.  
           [0014]    In yet another embodiment, the base is an upright planar member having a segment from which the retainer extends along a plane of the planar member. Preferably, this base also includes at least two additional upright segments extending at an angle to the planar member, and both of the segments include an upper serrated edge.  
           [0015]    In another form the invention provides an assembly for burning a fumigant. A burnable coil structure containing a fumigant is mounted on one of the supports described above with a first portion of the retainer being under a central portion of the coil structure, a second portion of the retainer passing through a central portion of the coil structure, and a third portion of the retainer passing over a central portion of the coil structure and also over at least part of the first portion of the retainer.  
           [0016]    In still another form the invention provides a method for burning a fumigant. One obtains one of the assemblies described above, and then lights the coil structure adjacent a radially outward portion of the coil structure.  
           [0017]    The preferred backing is a cellulosic (e.g. paper) backing layer in the form of a disk. However, the present invention also is well suited for use with even standard type coils. When the coil structure is used to control mosquitos, the coil portion is preferably a spiral substrate impregnated with an insecticide or insect repellant. We prefer a formulation of about 0.1% insecticide (e.g. esbiothrin or pynamin forte), 0.5%-5% charcoal, 1%-10% calcium carbonate, 0.1% dye and the remainder wood pulp. The coil can be made less than 2 mm thick and be supported on a thin continuous backing layer made from newsprint stock.  
           [0018]    The stands of the present invention are preferably made of a steel wire or steel sheet metal, but could be made from other metal and non-metal materials as well. Given the environment in which these stands are to be used, it is important that the stands be fire resistant. Apart from this, materials can be selected to minimize cost. These stands use reduced amounts of materials, and are easy to form. They are light weight to ship, and some can even be stored and shipped in a flat state.  
           [0019]    Thus, the present invention provides an inexpensive product to support a burnable coil structure while minimizing snuffing. The foregoing and other advantages of the invention will appear from the following description. In that description reference is made to the accompanying drawings which form a part hereof and in which there is shown by way of illustration preferred embodiments of the invention. These embodiments do not represent the full scope of the invention. Thus, the claims should be looked to in order to judge the full scope of the invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]    [0020]FIG. 1 is a top perspective view of a first stand of the present invention supporting a burnable coil structure;  
         [0021]    [0021]FIG. 2 is a view similar to FIG. 1, but with the coil structure shown in phantom;  
         [0022]    [0022]FIG. 3 is an enlarged side view, partially in section, taken along line  3 - 3  of FIG. 2, of a clip retainer portion of the assembly of FIG. 1;  
         [0023]    [0023]FIG. 4 is a view similar to FIG. 2, but with a different stand being shown;  
         [0024]    [0024]FIG. 5 is a view similar to FIG. 3, but taken along line  5 - 5  of FIG. 4;  
         [0025]    [0025]FIG. 6 is a top perspective view of a third stand embodiment, again with the coil structure shown in phantom;  
         [0026]    [0026]FIG. 7 is a view taken along line  7 - 7  of FIG. 6;  
         [0027]    [0027]FIG. 8 is a top perspective view of a fourth stand embodiment, again with the coil structure shown in phantom;  
         [0028]    [0028]FIG. 9 is a view similar to FIG. 3, but taken along line  9 - 9  of FIG. 8;  
         [0029]    [0029]FIG. 10 is top perspective view of a fifth stand embodiment, again with the coil structure shown in phantom;  
         [0030]    [0030]FIG. 11 is a view similar to FIG. 3, but taken along line  11 - 11  of FIG. 10;  
         [0031]    [0031]FIG. 12 is a top perspective view of a sixth stand embodiment, again with a coil structure shown in phantom; and  
         [0032]    [0032]FIG. 13 is a view similar to FIG. 3, but taken along line  13 - 13  of FIG. 12. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0033]    The stands of the present invention are particularly well suited for use with extremely thin burnable coils, such as the mosquito coil  10  shown in FIG. 1. These coils have desired burning characteristics (e.g., burn period, burn rate, etc.), and reduce the space taken up and weight of the product.  
         [0034]    The coil is formed of a substrate  12  and is supported at its bottom side by a backing  14  of newsprint stock. While a continuous sheet of paper is preferred for this purpose, alternatively the paper could only extend directly under the coil.  
         [0035]    As is conventional, the coil  10  has an outer burn end  18  which can be lit with a match or lighter until it begins a self-sustainable burning. The coil  10  spirals inwardly to an enlarged J-end  20  that is approximately in the center of the coil  10 . If desired, the end could be made bulbous and a hole  22  of about 4-10 mm diameter could be formed directly through the bulbous end (as shown in FIG. 1). However, it is preferred that the hole instead be positioned between the legs of the end J through the paper.  
         [0036]    For mosquito coils, the substrate  12  is preferably impregnated or coated with a suitable insecticide active ingredient or other types of active ingredients, such as known insecticides and insect repellants, that release when the coil is burned (e.g. esbiothrin, pynamin forte, transfluthrin). Alternatively, the coil substrate could be treated with other heat-releasable active ingredients, such as fingicides or deodorizers, fragrances and the like, for use as an aroma dispenser.  
         [0037]    The figures show various preferred embodiments of a stand designed to support the above described coils during burning. While the various disclosed embodiments have differing structures, they all include a retainer feature designed to make line contact (at least) with a center bottom portion of the coil structure.  
         [0038]    Referring specifically to FIGS.  1 - 3 , a first preferred coil stand  30  is made from a steel wire forming a base  32  and a clip  34 . The wire has a looped catch end  36  through which an intermediate point of the wire is disposed to form a generally circular ring defining the base  32 . A riser portion  38  extends inward and upward to a clip end  40  approximately above the center of the base  32 .  
         [0039]    The clip end  40  is bent in hairpin fashion to form two extension arms  42  and  44 , with the bottom extension arm  42  being generally parallel to the base  32 . The upper extension arm  44  can be formed with undulations and a curled back tip  46  (as best shown in FIG. 3). The clip extension arms  42  and  44  define a narrow slot  48  there between with an open mouth  50  at one end.  
         [0040]    The coil structure  10  is clipped to the stand  30  by inserting the curved back tip  46  through the opening  22  in the coil structure  10  and sliding a part of the central portion of the coil structure  10  into the slot  48 . In this way, the bottom clip extension arm  42  supports the bottom side of the coil structure  10  in line contact along the length of the bottom clip extension arm  42 . However, because there is a layer of paper between the wire and the coil structure  10 , and because the wire extends only a short distance in one direction, the snuffing potential is low due to this feature.  
         [0041]    The upper clip extension arm  44  can similarly make line contact with the top side of the coil structure  10  along the low sections of the undulations. The short distance of the top arm  44 , and the undulations, help reduce snuffing potential due to that feature.  
         [0042]    Thus, the coil structure  10  is securely clipped to the stand  30  at the top and bottom along the short width of the clip  34 . While this provides sufficient support to prevent the coil structure  10  from sagging too far, it only contacts the center of the coil structure  10 , and in line contact at that, so as not to snuff the coil structure  10  when burning.  
         [0043]    An alternative stand embodiment  30 A is shown in FIGS. 4 and 5. Elements similar to the above described embodiment are referred to similarly, albeit with the suffix A. Stand  30 A is a wire “gallows” type frame formed of a base  32 A, a clip  34 A and a riser portion  38 A. Base  32 A has a pair of generally co-planar legs  52  and  54 , preferably with only an acute angle there between.  
         [0044]    The wire is bent so that leg  54  comprises two oppositely extending runs of wire. The riser  38 A extends upwardly from the intersection of the legs  52  and  54 . The riser  38 A begins extending radially outwardly from the legs  52  and  54 , then bends inwardly and upwardly (then slightly downwardly)to the clip  34 A, which is above the base  32 A and between the legs  52  and  54 .  
         [0045]    Referring to FIG. 4, it can be seen that the clip  34 A has two generally parallel clip extensions  42 A and  44 A defining a slot  48 A there between with an open mouth  50 A. The end of clip extension  42 A is preferably bent downwardly away from clip extension  44 A.  
         [0046]    Coil structure  10  is clipped to the stand  30 A through the center opening  22 . However, here the riser  38 A runs to the clip  32 A from above the coil structure  10  so as to “hang” the coil structure  10  from above, rather than support it from below. Specifically, the bent end of clip extension  44 A is inserted into the opening  22  in the coil structure  10  from above and a portion of the coil structure  10  is pulled into the slot  48 A until it contacts the closed end of the clip  34 A. In this position, the coil structure  10  is securely suspended due to the line contact between the clip extensions  42 A and  44 A and the respective bottom and top of the coil structure  10 .  
         [0047]    A third stand embodiment  30 B is depicted in FIGS. 6 and 7. Elements similar to the above described embodiments are referred to similarly albeit with the suffix B. Unlike the above embodiments, stand  30 B is made of a suitable sheet material (e.g. sheet metal), rather than wire. The stand  30 B is preferably generally a triangular section with upwardly angled corners  60  being part of base  32 B.  
         [0048]    A tab  62  is cut out along three sides from the center of the base  32 B and is bent upwardly. The tab  62  forms a riser  38 B with a clip  34 B having a clip extension  44 B defining a lateral slot  48 B having a open mouth  50 B. Preferably, the bottom of the slot  48 B is in generally the same lateral plane as the tips of the bent up corners  60 .  
         [0049]    Referring more particularly to FIG. 7, the coil structure  10  is clipped to the stand  30 B by inserting the clip extension  44 B into the center opening  22  of the coil structure  10  and sliding the coil structure  10  to the end of the slot  48 B. Here again, the coil structure  10  is supported in line contact at the top and bottom sides. Additionally, the bent up corners  60  can support the coil structure  10  from below at three remote locations radially outward from the center if the coil structure should sag slightly. The corners  60  make as little point contact as possible.  
         [0050]    A fourth stand embodiment  30 C is shown in FIGS. 8 and 9. Elements similar to the above described embodiments are referred to similarly albeit with the suffix C. Stand  30 C is also made from a metal sheet material forming an E-shaped structure laid flat, albeit with the middle leg bend upward. In particular, the sheet material forms a base  32 C having generally coplanar parallel legs  52 C and  54 C extending laterally and connected at one end by a section of sheet material from which a middle leg  56  (forming the riser  38 C) extends upwardly to a clip  34 C. The clip  34 C is a bent back section forming two lateral extensions  42 C and  44 C defining a slot  48 C there between with an open mouth  50 C at one end.  
         [0051]    Referring to FIG. 9, a coil structure  10 ′, having a larger opening  22 ′ than coil structure  10 , is clipped to the stand  30 C by inserting clip extension  44 C into the opening  22 ′ and sliding the coil structure  10 ′ to the end of the slot  48 C. As before, the coil structure  10 ′ is supported at its top and bottom sides. However, here the clip  34 C makes surface contact with a small portion of the center of the coil structure  10 ′.  
         [0052]    A fifth stand embodiment  30 D is shown in FIGS. 10 and 11. Elements similar to the above described embodiments are referred to similarly albeit with the suffix D. Stand  30 D is made from a sheet material forming a base  32 D having an convex upper surface  80  and two arcuate upright sides  82  (one shown). A tab  86  is notched out of the center of the convex upper surface  80  and is bent upward slightly to define a riser  38 D and a clip  34 D. The tab  86  includes a lateral slot  48 D having an open mouth  50 D.  
         [0053]    Referring to FIG. 11, the coil structure  10 ′ is clipped to the stand  30 D by inserting the tab  86  into the opening  22 ′ and sliding the coil structure  10 ′ to the end of the slot  48 D. Here, the clip  34 D (at the underside of the tab  86 ) makes surface contact with a top portion of the coil structure  10 ′ and the base  32 D (at the convex surface  80 ) makes surface contact with a bottom portion of the coil structure  10 ′.  
         [0054]    A sixth stand embodiment  30 E is shown in FIGS. 12 and 13. Elements similar to the above described embodiments are referred to similarly albeit with the suffix E. Stand  30 E is formed of an elongated section of metal sheet material folded into three convoluted upright segments  90 ,  92  and  94 , forming a base  32 E. The segments  90 ,  92  and  94  have a serrated upper edge  96 . Also, segments  90  and  94  each have a projection  98  extending upwardly from the serrated upper edge  96 . In the middle of segment  92  is a flat (non-serrated) upper edge  100  where a clip extension  44 E runs parallel thereto to define a slot  48 E there between having an open mouth  50 E at one end, thus forming a clip  34 E.  
         [0055]    Referring to FIG. 13, a coil structure  10 ″, having a small opening  22 ″ (as in coil structure  10 ) and a pair of small remote openings  23 , is clipped to the stand  30 E by inserting the clip extension  44 E through the opening  22 ″ in the coil structure  10 ″ and sliding the coil structure  10 ″ to the end of the slot  48 E. The coil structure  10 ″ can be rotated, if needed, to align the remote openings  23  with the base projections  98  so that they can be inserted therein. The stand  30 E thus supports the coil structure  10 ″ at the center as well as at remote locations radially outward from the center. As before, the clip  34 E makes line contact with center portions of the top and bottom sides of the coil structure  10 ″.  
         [0056]    Thus, the present invention provides a stand particularly well suited for supporting large-diameter, low-profile burnable coils. The stand can take various forms, all of which can be formed from inexpensive materials and include a retainer feature that makes line or surface contact with a portion of the coil center to support it securely in the air during use without snuffing the burning coil.  
         [0057]    While specific embodiments have been shown, various modifications falling within the breadth and scope of the invention will be apparent to one skilled in the art. Thus, the following claims should be looked to in order to understand the full scope of the invention.