Abstract:
A sandal production method includes the application of a primer applied, preferably by wiping, to the latex or other printing surface of a sandal blank structure which may be applied and then wiped from the latex surface. The sandal shaped polymeric mass may be cut from a sheet of dense polymeric material, it may include sandal strap bores, and may have layers of flexible paint (preferably white) applied. A jig is disclosed for providing a support for multiple primed sandal blanks to save time in the printing process. Treatment of the printed sandal support with a protective overlayer is taught.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to improvements in the field of photographic quality images applied to wear surfaces and more particularly to a method of high quality image preservation on the upper wear surface of footwear which will permit inexpensive customized image placement which is long wearing and highly resistive to diminution of the image. 
       BACKGROUND OF THE INVENTION 
       [0002]    Printing on surfaces using a radiation and sometimes UV curable color inks to produce photographic quality images has been well known. Most radiation curable inks are used for fresh substrates which are new, clean, debris free and have surfaces that are amenable to bonding with radiation curable inks which are predominantly organic. The process of printing on objects which are not always fresh and clean is not nearly as well known nor as uniform as the use of fresh surfaces associated with signage, for example. 
         [0003]    Few references deal with surface preparation as a problem, simply because of the fact that radiation curable inks and printers deal largely with materials and surfaces for which surface preparation has not been problematic. However, one of the earlier references outlining the problems in printing on some objects was “PRIMED SUBSTRATES COMPRISING RADIATION CURED INK JETTED IMAGES” which issued on Apr. 13, 2004 to Ylitalo, et al., recognizes that “one problem, however, with radiation curable ink jet inks is that ink compositions do not uniformly adhere to all substrates,” and discusses the use of primers. Ylitalo recognized that “good wetting and flow onto various substrates is controlled by the ink/substrate interaction.” The Ylitalo reference cited a number of substrate treatments including “solvent wiping, blowing, corona, flame and UV pre-treatment have been suggested in “Practical Considerations for Using UV Reactive Inks in Piezo DOD Printheads”, Richard J. Baker, Spectra Inc., Hanover, N.H., USA, IS&amp;T&#39;s 15th International Congress on Advances in Non-Impact Printing Technologies (1999), pp 111-115, Conference on Digital Printing Technologies.” 
         [0004]    Paraphrasing, the problem faced by Ylitalo involved attempts to create an overall improvement in print quality as compared to an unprimed surface, with the result of about 50% to 80% adhesion, although the unprimed adhesion percentage was omitted. In most cases, Ylitalo used unprimed support structure surfaces including a film-forming resin comprising an acrylic resin, a polyvinyl resin, a polyester, a polyacrylate, a polyurethane and mixtures thereof, with the acrylic resins, polyurethane resins and mixtures thereof being preferred. 
         [0005]    Primers used by Ylitalo on such unprimed substrates were stated to have included cross linked poly(meth)acrylate, a colorant, a water-based primer composition or a solvent-based primer composition to at least a portion of a sheet or polymeric substrate; allowing the water or solvent to evaporate forming a primed surface; ink jet printing a radiation curable ink composition on said primed surface; and curing said ink forming an imaged article. The Ylitalo primer composition was stated as preferably an acrylic resin, a polyurethane resin, or mixture thereof. Ylitalo further taught a method comprising applying a radiation curable primer composition to at least a portion of a sheet or polymeric substrate forming a primed surface; ink jet printing a radiation curable ink composition on said primed surface; and curing said ink forming an imaged article, and including possibly curing the primer prior to ink jet printing. Ylitalo was concerned only with durability for outdoor usage, and thus against weather elements. Ylitalo stated that his primed surface encourages an ink to diffuse into the primed surface, but may or may not react with the primed surface. 
         [0006]    However no references have been seen which deal with priming of a flexible heavy polymeric object upon which a flexible latex has been applied. The problems encountered with sandals is many-fold. The base material of the sandal is typically jet-black hardened polymeric rubber. In order to have a surface which can show a full color image, it is necessary to provide a white layer which completely covers any of the black background and which is a bright white color so that the full range of color intensities can show through. The material chosen has to be as flexible as sandal rubber under conditions of normal wear, which will be significant. The bright white color has to be flexible enough to resist cracking. 
         [0007]    It has been discovered that a latex layer upon which radiation curable ink is applied will not be as wear resistant as desired for sandal applications. The applied image, which will be nearly fully appear when the sandals are not worn, undergoes significant and direct wear forces when the sandals are worn by a user. The purpose for applying a radiation curable ink is for enhanced appearance and novelty value. However, sandals which have an applied layer of radiation curable ink and which are worn can cause the removal of the ink image. Without the ability for a long lasting, resilient, wear-proof radiation cured ink image, the practical ability to provide images on sandals will be impractical. 
         [0008]    Even were the problem of applied ink image solved, the overall problems associated with manufacturing sandals with applied ink images has remained. Most radiation cured ink application machinery is designed for fresh, thin, flat sign material. Some flatbed printers have vacuum tables to hold the sign material flat to insure that the focus and distance of the application heads remains a constant, controlled fixed distance from the surface to be printed. Thong style sandals are available in a variety of shapes and thicknesses causing a significant production problem. Methods and structures which create production efficiency are needed. 
       SUMMARY OF THE INVENTION 
       [0009]    A sandal production method includes the application of a primer applied, preferably by wiping, to the latex printing surface of a sandal structure. The sandals referred to herein are of the type characterized by a main lower foot following polymeric mass with straps which have been known as flip-flop type footwear. The primer may include trisodium phosphate, dipropylene glycol monomethyl ether, dipropylene glycol n-butyl ether, and more. These and other primers may be obtained through commonly available commercial products containing these and other primers or wiping solvents, and may include commercially available Savogran 10632 TSP Liquid Substitute, Savogran 10621 TSP, Klean Strip QKTP06 Tri Sodium Phosphate Substitute, and Bona Stone Tile and Laminate Floor cleaner. The primer is applied and then wiped from the latex surface. It is believed that the mechanism which allows radiation cured inks to work with a latex surface involves the formation of a less porus and smoother surface for radiation cured inks to be deposited. However, it is unclear whether the superior fixation of the ink to the latex photo deposition surface is through surface smoothing, leaving of some primer residue to interact with the radiation cured inks, the promotion of an inter-bond relationship between the latex and the radiation cured ink and perhaps other mechanisms not yet identified and not verified. 
         [0010]    In terms of processing to create a sandal, a sandal shaped polymeric mass may be cut from a sheet of dense polymeric material having a thickness of from about 1 to 3 centimeters. It may also be typical for the sandal strap bores (typically three) to be cut simultaneously or just after the formation of the sandal shaped polymeric mass. The sheet will typically have a bottom sole pattern and a top surface which may or may not have been processed to a smooth closed foam polymeric shape. The top of the sandal shaped polymeric mass may have a layer of flexible paint (preferably white) applied, or it may have a white coating or applied structure of any type. The upper coating or added overlay surface (which may be a layer of attached material) provides a smoother and more even surface for printing and provides a more complete covering and closure for any open foam-type cells or defects in the upper surface of the sandal shaped polymeric mass. The sandal shaped polymeric mass with upper applied surface addition can be referred to as a sandal blank which is ready for printing. 
         [0011]    An improved positioning and hold-down jig is used to provide a uniform target surface with minimum loss of radiation cured ink, and conserves machine cycling by providing a wider travel period for the radiation cured ink jet of a flatbed scanner. A jig can provide custom fit for several primed sandal blanks to make an effective elongated travel path for an ink jet printing head. Because the ink jet printing head is computer controlled, the printing can produce different styles and patterns across the line of grouped sandal blanks. The jig further reduces the number of times that the ink jet printing head stops and restarts per individual sandal blanks. The jigs also provide a support for loading and unloading groups of finished, printed sandal members which will enable workers to load and unload other jigs while the scanning flatbed printer is printing another set of jigs supporting many sandal blanks. 
         [0012]    An improved positioning and hold-down jig may have a series of openings sized to snugly fit the sandal blanks in a predetermined orientation as closely spaced as the radiation curable ink printer head will allow in terms of its adjustment time and isolation of printing of adjacent print targets. Where the jig has through openings to support the sandal blanks, and especially where the flatbed printer has a partial vacuum hold down capability it may be preferable to cover the sandal strap bores of the sandal blank on its underside to help preserve the partial vacuum hold down capability of the flatbed printer support. Adhesive tape or other occluding structure can be used. A jig with through openings helps in removal of the printed sandal base after printing. 
         [0013]    A closed back jig can be used, but causes some extra care to keep the closed space in which the sandal blank will be placed in a clean, debris free state. Further, care should be taken in removal of the printed sandal support from the closed back jig as removal might be more difficult. The printing process takes a few minutes and thus it is possible for one worker to load the flatbed printer and then unload the printed sandal supports from the jigs and reload the jigs with sandal blanks with time left over before the printing cycle is finished. 
         [0014]    An overlayer, such as can be applied as a finishing layer over the top surface of the printed sandal support. The use of an overlayer can assist in a number of areas. First, any fixable layer which overlies the radiation cured ink will help protect it against direct wear. Second, where it is desired to give a surface effect to the printed sandal support, including both the ink and non-ink areas a covering layer is useful. The covering layer can have its own particulate suspension, including color, reflective glitter, and the like. In addition, where the ink design is not made to cover the entire surface of the printed sandal support, a covering layer will help seal the outer edges of the design where it lies adjacent un-coated upper surface areas. A coating overlayer can include a flexible aliphatic urethane. 
         [0015]    If an overcoating is used, it may be applied to the printed sandal support while it is supported by or once it has been removed from the support jig. Once the printed sandal supports, with or without an overcoating have been removed from the jig, a tool can be used to insert the sandal straps into the strap openings in sandal support to form a completed &amp; finished sandal. 
         [0016]    The inventive methods herein can be utilized to produce a custom sandal having photographic quality images including photographs, logos and art work. It is possible to produce a custom sandal for one customer having photos of his or her choice and which can be made alongside a number of sandals having corporate logos or made as gifts and party favors. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    The invention, its configuration, construction, and operation will be best further described in the following detailed description, taken in conjunction with the accompanying drawings in which: 
           [0018]      FIG. 1  is a perspective view of an underside of an sheet of sheet of heavy polymeric or elastomeric material having a tread pattern underside and from which a sandal shaped elastomeric mass is cut leaving a central sandal shaped void; 
           [0019]      FIG. 2  is a perspective view of the sandal shaped elastomeric mass of  FIG. 1  and illustrating an overlayer which may be a series of layers of flexible latex paint to completely cover the sandal shaped elastomeric mass; 
           [0020]      FIG. 3  is a plan view of a view of the sandal shaped elastomeric mass of  FIG. 2  having an upper coating which may preferably be a latex coating, and shown undergoing surface preparation with the use of a spray nozzle and wipe cloth; 
           [0021]      FIG. 4  is a plan view of a jig having sandal shaped openings to support sandals in a pre-specified, known orientation and having an easily checked flat upper profile to help workers to visually inspect for a flat printing profile; 
           [0022]      FIG. 5  is a schematic downward view looking down upon the top of a flat-bed printer and illustrates the use and placement of a jig and illustrates two sandal blanks loaded into the jig and ready for the printing operation to begin; 
           [0023]      FIG. 6  is a sectional view taken along line  5 - 5  of  FIG. 5  and illustrating a cross section of a sandal blank or printed sandal support held in the jig and showing the pair of rear strap bores as having chamfered lower openings; and 
           [0024]      FIG. 7  illustrates a plan view of a completed printed sandal with prominent images and sandal strap set applied. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0025]    Referring to  FIG. 1 , a sheet of heavy polymeric or elastomeric material  21  having a thickness of from about 1 to 3 centimeters is seen from its underside. A tread pattern underside  23  is seen and may be any pattern appropriate for a sandal which may provide some anti-slip characteristic. A central sandal shaped void  25  remains after cutting and removal of a sandal shaped elastomeric mass  27  having a top side  29  facing the viewer of  FIG. 1 . Also seen are a series of three sandal strap bores including a forward strap bore  31  and a pair of rear strap bores  33 . The bores will preferably have an expansion chamfer on the bottom side (not seen in  FIG. 1 ) opposite top side  29 . The cut-out and formation of the sandal shaped elastomeric mass  27  may be such that bores  31  and  33  and any expansion chamfers on the bottom side (not seen in  FIG. 1 ) may be formed in a single process operation. 
         [0026]    Referring to  FIG. 2 , a perspective view of the sandal shaped elastomeric mass  27  shows it has having an upper applied surface  39  of preferably bright white color and which may be provided as an additional overlayer applied to the top side  29  of the sandal shaped elastomeric mass  27  seen in  FIG. 1 . The upper applied surface  39  may be a surface possibly of a plurality of layers of coatings of which three are seen as layers  41 ,  43 , and  45 , or simply one such upper layer of material  45 . The three layers  41 ,  43 , and  45  may also preferably be three layers of a flexible, white, latex paint. A white upper surface  39  will enable printing to be performed in an array of colors, as all colors can be derived by printing. Starting with a white upper applied surface  39  enables a printer to form a pattern with same or better quality that a pre-printed upper layer of material  45  might be acquired. 
         [0027]    It may also be that applying a flexible latex paint in layers will improve the flexibility and resiliency and brightness a resulting upper top side  29 . It may be possible for a single layer  45  to be utilized provided it has sufficient thickness of a sufficient opaque quality to block out any light or brightness absorbing effect of the material from which the sandal shaped elastomeric mass  27  is formed. In any event the upper top side  29  seen in  FIG. 2  should be sufficient in terms of brightness and flexibility, for printing. It makes no difference for the purposes of further discussion whether a number of layers  41 ,  43 , and  45  or a single layer form the top side  29 . 
         [0028]    Referring to  FIG. 3 , a plan view of a view of the sandal shaped elastomeric mass  27  of  FIG. 2  having an upper coating of at least one of layers  41 ,  43 , and  45  which coating may preferably be a latex coating or other suitable surface applied to and forming part of the top side  29  represents a sandal blank  51  ready for surface treatment, and may be referred to as a sandal blank  51 . It is expected that the sandal blank  51  may be available to some image printers in this form, with layers  41 ,  43 , and  45  or at least one bright white layer  45  ready for printing. Sandal blank  51  is shown in a position for undergoing surface preparation where necessary or desirable. Surface preparation may include a spray mechanism  53  for applying a thin layer of a surface preparation solution, such as a liquid  55 , over preferably a wide area of the sandal blank  51 . After initial application of liquid  55  and preferably while the upper applied surface  39  is still wet with the liquid  55 , a wiping structure  55  which may be a cloth, paper towel, sponge, squeegee or other structure is used wipe the upper applied surface  39 . The wiping action provides some swiping pressure to the upper applied surface  39 , provides cleaning to upper applied surface  39  and also helps remove any debris from the upper applied surface  39 . The wiping action may leave some residue by evaporation action to help a radiation cured ink bond with upper applied surface  39 . All aspects of the mechanism of applying and wiping may not be fully known, but the results have been effective in providing a higher adhesion of the radiation cured inks. 
         [0029]    After the wiping operation seen in  FIG. 3 , the sandal blank  51  is ready for printing. Most of the radiation cured ink printing occurs on a flat bed scanner (to be shown) with a printing housing which moves back and forth in raster fashion as moves minutely forward and advances a front of a series of thin lines of color radiation cured ink across a surface to be printed, which in this case is the upper applied surface  39 . However, precise printing of photographic quality images requires a sandal blank  51  upper applied surface  39  which has a consistent and known orientation on the flat bed support of the flat bed scanner (not yet shown). Further, the height of the surface to be printed must also be controlled. Referring to  FIG. 4 , it has been discovered that one structure which can supply this stability and consistency is a sandal blank  51  support jig  61 . Support jig  61  may preferably have a height thickness which matches the height thickness of the sandal blanks  51  it will support. 
         [0030]    The jig  61  has a series of openings including a large openings  63  for large size sandal blanks  51 , a small size openings  65  for medium size sandal blanks  51 , and a medium size openings  67  for medium size sandal blanks  51 . Now the openings  63 ,  65  and  67  are arranged in pairs for illustration purposes but need not be so arranged. Different sizes are shown on the jig  61 , but a given jig  61  need not have but one size. The numbers of openings  63 ,  65  and  67  in a given jig  61  can be numerous. Jig  61  is shown as having opposite ends  71  which are shown in broken line format to represent the fact that jig  61  can be much longer in either direction with such lengths containing additional openings  63 ,  65  and  67 . Jig  61  is shown as having a side  73  which is shown in broken line format to represent the fact that jig  61  can have further rows containing additional openings  63 ,  65  and  67 . 
         [0031]    The openings  63 ,  65  and  67  can have any pre-determined orientation, including a densely packed orientation which minimizes the material between the openings  63 ,  65  and  67 . The consideration in making a more densely packed jig  61  with seemingly more random arrangement of the openings  63 ,  65  and  67  is the material from which jig  61  is constructed and to insure that the printing control software can be made to accommodate. The considerations in a design of a jig  61  are thus the material of construction, the overall size, and the savings which can result from a printer of a given size, as well as the investment I a larger size printer. The use of a stronger material will enable more closely spaced openings  63 ,  65  and  67  but may create handling problems relating to bending and breaking, as well as a combined loaded handling weight, including sandal blanks  51 . 
         [0032]    Referring to  FIG. 5 , an overhead schematic view of a flat-bed printer  81  is shown. The flat-bed printer  81  has a support table  83  and may have various size and shape openings (not shown) for introducing a partial vacuum to assist in hold down of any object placed on the flat-bed printer  81 . The flat-bed printer  81  portion shown is isolated to a central portion and a pair of sides  85  are shown in broken line format to represent that the support table  83  and other associated structures may exist a wide distance away from the portions of the support table  83  shown, as well as to eliminate the need to show details of motion control housings at the far ends of the support table  83 . 
         [0033]    The support table  83  may preferably have a positioning stop rail  87  against which the jig  61  may be positioned to ensure that the jig  61  can be located in a constantly identified rearward position when placed upon the support table  83 . Lateral stop members may also preferably be used but are not shown in order to simplify the explanation and would be normally located beyond the central portion of the flat-bed printer  81  illustrated in  FIG. 5 . 
         [0034]    Near the top of  FIG. 5 , a pair of support rails  89  are seen as supporting a radiation curable ink printer head housing  91 . Printer head housing  91  may be preferably equipped with a multi-color printer head and with at least one radiation curing light source. In a typical setup, the printer head housing  89  moves back and forth along the pair of support rails  89 . The pair of support rails  89 , by virtue of other motion control structures located beyond the pair of sides  85  and is not shown in  FIG. 5 . The pair of support rails  89  move in a direction toward or away from the positioning stop rail  87  to position the printer head housing  89  for the next movement along the support rails  89 . 
         [0035]    The result is a raster action with the main motion occurring by the printer head housing  91  as a reciprocating motion which occurs along the support rails  89  sufficient to overlie the width of sandal blanks  51 . The minor motion occurs by lateral movement of the pair of support rails  89  to prepare the printer head housing  89  for its next reciprocating sweep, and this lateral movement of the support rails  89  movement is typically very small, on the order of from one half to three millimeters per completed reciprocation of the printer head housing  89  along the pair of support rails  89 . In a typical setup, the lateral movement of the pair of support rails  89  will start at one side of the table  83 , and either closer to or farther from the positioning stop rail  87 , for example, until all of the surface to be printed that is present is printed. 
         [0036]    Referring to  FIG. 6 , a cross section of the jig  61  shown in  FIG. 4  and taken along line  5 - 5  is shown. The jig  61  is shown has having had two of its large openings  63  loaded each with a sandal blank  51  and ready for printing. Jig  61  has a generally planar upper side  93  and a generally planar lower side  95 . Note that the upper applied surface  39  is seen as preferably flush with respect to the generally planar upper side  93  of the jig  61 . The jig  61  openings could be closed along the bottom side, thus providing an enclosure on three sides for supporting the sandal blank  51 , but it is believed to be preferable to use openings  63 ,  65 ,  67  to be through openings. A first disadvantage a closed bottom jig is that the personnel loading the sandal blanks  51  would not be continually pushing against a thin wall at the rear of the jig  61 , and possibly encounter debris there. A second disadvantage is that the unloading of a printed sandal support from the sandal blank  51  would involve trying to lift a secured body that may preferably be generally flush with the top of the jig  61  causing printing personnel to either have to resort to prying the secured body out or trying to engage one of the forward strap bores  31  or pair of rear strap bores  33 . 
         [0037]    There are a number of advantages to having through openings  63 ,  65 , and  67 . First it enables printing personnel to more readily remove the printed sandal supports (not yet shown) by pushing them up and out of the openings  63 ,  65 ,  67  once printing is completed. Second, no debris can collect as there is no closed space. Third, when the jig  61  is loaded onto the flat-bed printer  81 , the printing personnel can visually inspect the upper side  93  of the jig and make sure that it is flush with the upper applied surfaces  39  of the sandal blanks  51  prior to printing. Any sandal blank  51  which is not flush can be pressed down until it is flush or else be quickly removed as a defective sandal blank  51 . 
         [0038]    Controlling the height of the radiation cured ink ejector over the printing surface is important to producing a high quality printed sandal support. A upper applied surface  39  of a sandal blank which is too close or too far from the expected distance from the ink ejector will produce a blurred or uneven image.  FIG. 6  also illustrates that each of the pair of rear strap bores  33  includes a chamfer  97  at the lower opening of the bores  33 . The strap bores  31  have a chamfer  97  also but it cannot be seen in  FIG. 6 . The chamfer  97  will accommodate a sandal strap button (not shown) which will act to stably hold a sandal strap set in place. It is realized that a vacuum applied to the bottom of the view of  FIG. 6  would result in a sacrifice of the vacuum due to air being drawn through the forward strap bore  31  (not shown in  FIG. 6 ) and pair of rear strap bores  33 . The simple expedient of covering the lower chamfer  97  openings with a weakly engaging masking tape or equivalent will prevent any loss of vacuum force due to the forward strap bore  31  and a pair of rear strap bores  33 , and is easily removed. 
         [0039]    It is preferable for the openings  63 ,  65 , and  67  of the jig  61  to be sized for a slight interference fit with the appropriately sized sandal blanks  51  in order that the jig  61  can be loaded and support the sandal blanks  51  while the jig  61  is being moved onto and off of flat-bed printer  81 . Even where the degree of interference fit will vary from one of the openings  63 ,  65 , and  67  to another, the interference fit should be sufficient to hold the sandal blank  51  stably and until it is forced from the jig from the underside. 
         [0040]    At the upper right of  FIG. 6 , spray nozzle  99  is shown and delivering a liquid to form a covering layer  101  to form covering layer to the upper applied surface  39  after the printing process has occurred. Covering layer  101  may be an aliphatic urethane, or similar material. Commercially available urethane products may include JFB Hart HP300 Aliphatic Urethane, Gemini Aliphatic Urethene Exterior Clear, Benjamin Moore Super Spec Aliphatic Acrylic Urethane Gloss, Sherwin Williams Diamond Clad Urethane Clear Coat, and PPG Pitthane 95-8800 Acrylic Aliphatic Urethane. Further, it may be advantageous to perform this covering layer while the printed sandal supports resulting from the printing of the sandal blanks  51  while they remain in position within jig  61 . The provision of an integrated flat surface made up of upper applied surface  39  which has just been printed and flush to generally planar upper side  93  of the jig  61  may facilitate application of a covering layer  101 . Further, in some instances it may be preferable to apply a liquid to form the covering layer  101  by brush or roller. The use of the jig  61  while applying a covering layer  101  would help combat drips or otherwise exposure of the sides of the printed sandal blank  51  to the liquid forming the covering layer  101 . 
         [0041]    Referring to  FIG. 7 , a completed printed sandal  111  is illustrated. A printed sandal support  113  is shown with a sandal strap set  115  attached to form the completed sandal  111 . A number of images  117  and  119  are seen as having been applied to the upper applied surface  39 . It is expected that the sharpness and integrity of the images  117  and  119  will withstand foot pressure, upper applied surface  39  compression and deformity throughout a significant portion of the completed sandal lifetime. 
         [0042]    While the present invention has been described in terms of a method of manufacturing a sandal with a wear-resistant, long lasting and high resolution graphic, and in particular an adjustable scale manufacturing method which enables an efficient manufacturing technique for both custom and long runs of production, the techniques described herein are applicable in a wide variety of production surroundings. The invention presents improvements in both printing, indexing of a product to be printed, and sandal production, as well as techniques for producing a high quality sandal product. 
         [0043]    Although the invention has been derived with reference to particular illustrative embodiments thereof, many changes and modifications of the invention may become apparent to those skilled in the art without departing from the spirit and scope of the invention. Therefore, included within the patent warranted hereon are all such changes and modifications as may reasonably and properly be included within the scope of this contribution to the art.