Abstract:
A wax molding toy uses a heat retaining housing with a transparent surface to provide wax melting temperatures with typical indoor solar flux intensities.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is based on U.S. Provisional filing No. 60/175,809 filed Jan. 12, 2000 and claims the benefit thereof. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The present invention relates to children&#39;s crayons and, in particular, to a device for sharpening and reforming broken or dull crayons using heat from the sun.  
           [0003]    Children&#39;s crayons employ a binder of wax to carry a non-toxic colored pigment. Although crayons offer a versatile and safe media for children, they have several drawbacks. The first is that the wax matrix is relatively soft so the crayon tip rapidly dulls. Further the crayon is easily broken, especially once the outer paper wrapper is removed.  
           [0004]    Mechanical sharpeners may be used to sharpen crayons. One form employs a canted blade hidden in a cavity. The crayon is sharpened by inserting the tip of the crayon into the cavity and rotating it against the blade. Repeated sharpenings reduce the length of the already short crayon, limiting the number of times the crayon can be resharpened.  
           [0005]    It has been proposed to sharpen crayons with a heated conical cavity. The crayon tip is pressed against the cavity, which melts its surface into a point. Whether or not such devices are practical, they are relatively expensive and require both a connection to an electrical source and the use of a heating element, both of which may be make the device unsuitable for young children. In any case, the drawback to mechanical sharpening, that of the crayon getting shorter, is not avoided.  
         BRIEF SUMMARY OF THE INVENTION  
         [0006]    The present invention provides a safe, entertaining and educational way to sharpen dull crayons and to mold crayon fragments into complete crayons using single or multiple colors. The need for electricity or dangerous heat source is eliminated by a design that uses sunlight passing through a window as the sole energy source. While the sun provides sufficient heat to melt the crayons, the total amount of energy remains relatively small ensuring that the molten wax presents relatively little danger to a child both in temperature and heat capacity.  
           [0007]    A device for practicing the invention may be inexpensively molded from a clear plastic such as polystyrene and may assembled from two molded mirror image shells so as to reduce molding costs. The shells may be held together by rubber bands to provide a safe and effective clamping. A suction cup may be used to hang the shells directly on a window eliminating the need for a nearby table or other support. The necessary insulation may be provided solely by air gaps within the shells eliminating the need for insulating foam or the like.  
           [0008]    The crayons may be formed in an elastomeric mold flexing to provide for easy release of the molded crayons. Interlocking ridges and sockets flexibly engage to provide a good seal against leakage of molten wax during operation. The mold may be longer than a standard crayon to accommodate the inevitable gaps between the fragments from which the crayons are molded and thus to produce a crayon of full length. The mold may provide an internal ridge to allow excess sprue to be snapped off.  
           [0009]    A temperature sensor composed of a liquid crystal device or a trap holding a fragment of wax may provide an indication of the temperature of the system.  
           [0010]    By orienting the broad face of the toy vertically, year round use may be provided in which low angled sun provides more direct illumination during winter months and high angled sun has a high angle of incidence, which reduces its heating effect.  
           [0011]    The entire toy may be readily formed by vacuforming or thermoforming techniques. A single piece thermoform shell may be used in conjunction with thermoformed front and rear panels to provide the necessary insulating and light transmitting properties or simple thermoformed shells may be used in combination with an opaque or other shroud. Molds may be thermoformed trays positioned so as to eliminate the need for tight sealing against the liquid wax. Forms other than crayons may also be formed such as medallions or the like. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    [0012]FIG. 1 is a perspective view of the toy of the present invention supported via a suction cup and hook on the inside face of a window;  
         [0013]    [0013]FIG. 2 is an exploded perspective view of the toy of FIG. 1 showing hooks by which the components of the toy are held together with elastic bands;  
         [0014]    [0014]FIG. 3 is a cross-section taken along line  3 - 3  of FIG. 2 of the assembled toy showing the sandwiching of an elastomeric mold within transparent opposed insulating shells;  
         [0015]    [0015]FIG. 4 is a detailed cross-section perpendicular to the cross-section of FIG. 3 showing a score line incorporated into the mold to facilitate the removal of the crayons sprue after molding;  
         [0016]    [0016]FIG. 5 is a cross-sectional view similar to that of FIG. 3 showing a cavity in the mold for supporting a temperature indicating material between the mold and one panel of the shell;  
         [0017]    [0017]FIG. 6 is a side elevational view of an alternative embodiment formed from a thermoformed tri-fold having laminated front and rear panels to provide for a double pane construction;  
         [0018]    [0018]FIG. 7 is a front elevational view of the embodiment of FIG. 6 when assembled showing placement of thermoformed tray molds within the cavity so produced; and  
         [0019]    [0019]FIG. 8 is a vertical cross section of the embodiment of FIG. 6 as placed against a window and having an opaque covering shroud in lieu of the front and back panels. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0020]    Referring now to FIG. 1, the molding toy  10  of the present invention has a generally rectangular body  20  such as may lie against an inner surface of a vertically oriented residential glass window  12  as held by a vinyl suction cup  14  having a metal hook. The hook of the suction cup may attach to an upwardly extending ear  18  positioned at a front edge of the body  20  and having a hole  22  for receiving the hook therethrough. A window-facing portion of the body  20  is transparent to allow sunlight to pass through to its inner volume.  
         [0021]    Referring now to FIG. 2, the ear  18  may be an extension of a front cover plate  24   a  being generally a six-inch rectangle of 0.055-inch polystyrene plastic. The front cover plate  24   a,  as shown in FIG. 3, includes an offset lip  26  allowing it to fit into an open face of generally rectangular front mold support  30   a.  The front mold support  30  (when it is installed on the front cover plate  24   a ), presents a central face behind and parallel to the front cover plate  24   a  approximately 0.4 inches away from the front surface of front mold support  30   a.    
         [0022]    The central face of the front mold support  30  is in turn surrounded on four sides by channel  32  extending away from the front cover plate  24   a.  The channel  32  is in turn surrounded by walls  34  extending toward the front cover plate  24   a  and engaging its offset lip  26 . The walls  34  thus support the front cover plate  24   a.  Front cover plate  24   a  and front mold support  30   a  may both be molded of the same polystyrene.  
         [0023]    The front cover plate  24   a  and front mold support  30   a,  when assembled, form a shell  42   a  enclosing an airtight volume. A second identical shell  42   b  formed by rear cover plate  24   b  and rear mold support  30   b  may be rotated 180 degrees with respect to its vertical axis so that a now front facing surface of channel  32   b  of shell  42   b  (corresponding to channel  32   a  of shell  42   a ) abuts the rear facing surface of channel  32   a  of shell  42   a.  The rear facing surface of the channel  32   a  and the front facing surface of channel  32   b  include a key and socket joint  38  having interengaging portions extending in or out of surfaces to align the shells  42   a  and  42   b  for assembly. In this joint, keys  38   a  of one-half of the perimeter of the channel  32   a  engaging the sockets  38   b  on an opposite one half of the perimeter of the channel  32   b  of sides of the shell  42   b  and key sockets  38   b  of the remaining-half of the perimeter of the channel  32   a  engaging the keys  38   a  on a remaining opposite one half of the perimeter of the channel  32   b  of sides of the shell  42   b.  In this way the shells  42   a  and  42   b  can be identical.  
         [0024]    The outer surfaces of the walls  34  of each of the shells  42   a  and  42   b  have outwardly extending hooks  36  such as may engage elastic bands  54  to hold the shells  42   a  and  42   b  together. The necessary pressure between the plate shells  42   a  and  42   b  may be adjusted by providing additional hooks  36  and elastic bands  54  as needed. Reinforcing ribs may be added to either of the front or rear cover plates  24  and mold support  30   a  or  30   b  to provide for additional rigidity in the body  20 .  
         [0025]    When assembled together, front mold support  30   a  of shell  42   a  and the corresponding rear mold support  3   b  of shell  42   b  are separated by their respective channels  32   a  and  32   b  to enclose an inner volume  51 . Extending into this volume from the mold supports  30   a  and  30   b  are guide ridges  40   a  and  40   b,  respectively, aligning and supporting an elastomeric mold  44 .  
         [0026]    The elastomeric mold  44  may be constructed of an opaque rubber material such as silicone rubber and may separate into a front mold half  47   a  and a rear mold half  47   b.  The front mold half  47   a  and rear mold half  47   b  join along a vertical interface to define four crayon-shaped mold cavities  48 , each being substantially 0.3 inches in diameter and 4.0 inches long to be approximately half an inch longer than a commercially available wax crayon but of equal diameter. The mold cavities terminate in a frusto-conical tip of the type adopted by commercial crayon manufacturers.  
         [0027]    Troth and ridge joints  50  are positioned around each of the mold cavities  48  to prevent the migration of molten wax from one cavity to the other or into the volume between front mold support  30   a  and rear mold support  30   b.    
         [0028]    In use, fragments of crayons or crayons in need of sharpening are placed within the mold cavities  48  which are then clamped between the shells  42   a  and  42   b  as held by elastic bands  54  on each of four sides of the shells  42   a  and  42   b.  The assembled molding toy  10  is then placed on the window  12  as supported by the suction cup  14 .  
         [0029]    Approximately one hour of noonday sun will melt the contents of the elastomeric mold  44  causing the molten wax to descend toward the frusto-conical tips of the mold cavities  48  of elastomeric mold  44  which are preferably pointed downward.  
         [0030]    Referring now to FIG. 4, some separation of the pigment from the wax matrix will cause a concentration of pigment toward the tip rendering an upper sprue  56  substantially free of pigment. The portion of the mold cavity  48  below the sprue  56  conforms substantially to the outline of a standard wax crayon 3.5 inches in length and includes beyond that point an inwardly extending annular ridge  58  which produces a circumferential groove between the sprue  56  and the remainder of the crayon to provide a point at which the sprue may snapped off. A circular bore (not shown) may be provided in one of the shells or both of the shells  42   a  and  42   b  to provide leverage for this snapping operation.  
         [0031]    Referring now to FIG. 5, a portion of one of the mold halves  46   a  or  46   b  may have a concave depression  60  to form a pocket between the mold  46   b  and rear mold support  30   b  that may be used to hold a fragment of crayon  62  whose melting will indicate the temperature of the elastomeric mold  44 . Likewise a thermometer or liquid crystal-type display may be placed at this point.  
         [0032]    Black paper collectors  64  may be placed within the volume between the shells  42   a  and  42   b  so as to provide additional heat absorbing capacity in winter months.  
         [0033]    The side of the collectors  64  toward the sun may be black and the side away from the sun may be a low emissivity surface such as white or foil.  
         [0034]    It will be understood that the elastomeric mold  44  may be used to make other shapes as well as conventional crayons out of wax and thus the toy forms a general purpose-molding device.  
         [0035]    Standoffs (not shown) may be molded into the front and rear cover plates  24   a  and  24   b  to hold the toy  10  away from the window during periods of low outside temperature so as to provide an additional insulating layer between the toy  10  and the window  12 .  
         [0036]    Instead of a two-part elastomeric mold  44 , the mold may comprise sleeves of highly elastic material that may be rolled back without seam to release the crayons.  
         [0037]    Alternatively, only the tips of the crayons may be molded using a small elastomeric mold and reusable handles embedded in the molten tips by projecting hooks. A high expansion co-efficient of these hooks would ensure the wax tips are held in tension against the handles, a mode of great strength for wax.  
         [0038]    As an alternative to the elastomer, the molds may be formed directly out of a rigid plastic or semi-rigid plastic with a suitable release surface or having a sufficient flexure to allow release of the molded crayons. Sleeves may be provided to roll about the crayons when they are formed or may be molded in place. Different colored crayons may be put into the molds to provide for various effects including streaking and/or laminated crayons of different colors depending on the mobility of the pigments.  
         [0039]    Referring now to FIG. 6, in an alternative embodiment of the molding toy  10 , a thermoformed tri-fold shell  70  of a type well known in the art, may provide two outwardly concave shells  72  and  74  joined at lower outer edges  76  by means of living hinge members  76  to a base  78  so that bottom surfaces  80  of the shells  72  and  74  may hinge together and be held abutting by post and socket members  82  of a type well known in the art of thermoforming.  
         [0040]    The abutting bottom surfaces  80  may be formed to produce inwardly facing cavities  84  such as may enclose molds  86  for holding crayon or other wax fragments.  
         [0041]    Referring now also to FIG. 7, the thermoformed material may be a transparent material to provide for the necessary influx of solar energy. Extending laterally inward from the sidewalls of the cavities  84  may be rails  88  also thermoformed as support the edges of the molds  86 .  
         [0042]    Referring again to FIG. 6, the molds  86  may have covering flaps  90  such as provide additional heat retention and are transparent to allow the influx of solar energy.  
         [0043]    Transparent front plates and rear plates  90  and  92  may be adhered to the outwardly facing lips of shells  72  and  74  to trap air about the cavities  84  so as to reduce heat loss.  
         [0044]    Referring now to FIG. 8, in an alternative embodiment, the tri-fold  70  of FIG. 6 may be used without front and rear plates  90  and  92  but attached directly to the window  12  by suction cup  14  so that the window itself provides a trapping of air between the cavity  84  and the window  12 . An opaque shroud  96  such as a cardboard box or the like may be placed over flanges  73  of the tri-fold shell  70  providing trapped insulating spaces  97  at the top and bottom of the toy and  98  to its rear. The opaque quality of the shroud  96  ensures complete capture of solar influx.