Abstract:
Protective headwear (e.g., helmet) is provided with patterned reflective surfaces that are highly reflective and resist rough handling. The reflective surface is produced by sealing a reflective sheet between a base and a cover layer that includes a pattern, to protect the reflective sheet from the environment. The protective headwear can reflect light in different colors. A method for cost-effectively producing reflective objects by injection molding is also provided.

Description:
FIELD OF THE INVENTION 
     The invention relates to protective headwear, for example, a helmet that reflects light. 
     BACKGROUND OF THE INVENTION 
     One conventional approach for producing a light-reflective object includes attaching a number of reflective decals formed on a paper or plastic base to the surface of these objects, for example with an adhesive. In other approaches, a reflective material is sprayed directly onto the object, for example through a patterned mask, or a desired pattern of the reflective material is formed and is then sewn on a fabric. The object is then covered with the fabrics. The reflective material can also be sewn directly onto the object. 
     The conventional approaches described above suffer from a number of disadvantages. One disadvantage is that the reflectivity of these surfaces can degrade prematurely since the reflective material is, in most cases, directly exposed to the environment, i.e., the ambient air, moisture, sunlight and dust. For example, if the reflective surfaces are formed of thin metal coatings, for example, silver or aluminum, such coatings tend to oxidize in air causing their reflectivity characteristics to degrade rapidly. An unprotected reflective surface can also be easily damaged and/or scratched upon contact with other objects, for example, when used in harsh environments, such as at a construction site. Reflective surfaces that are produced by spraying a reflective paint on the object, tend to have poor reflectivity and produce less vibrant colors. 
     Using an adhesive to attach reflecting decals on objects requires a large number of processing steps, such as printing, cutting and attaching. Thus, this approach is not cost-effective. Cutting and sewing is also required when the decals are attached to fabrics. 
     SUMMARY OF THE INVENTION 
     The invention relates to protective headwear having a light-reflecting surface with high reflectivity. In one aspect of the invention, the protective headwear includes a shell member having a molded base; a cover sheet, covering the molded base, with a pattern defined by areas that are transparent to the optical radiation passing through the cover sheet and other areas that are opaque to the optical radiation and a reflective sheet sealed between the molded base and the cover sheet from the environment. 
     Embodiments of this aspect of the invention may include one or more of the following features. The patterned structure can be formed directly on the cover sheet. Alternatively, the protective headwear may further include a separate patterned sheet that is arranged between the cover sheet and the reflective sheet. The cover sheet is preferably made of a plastic that is impervious to air and moisture. The reflective sheet can be a metal foil or a plastic sheet that is coated with a reflective metal. The reflective sheet can also have the form of a reflective dielectric stack. The reflective sheet and the cover sheet can have spectrally selective optical characteristics. The base can be in the form of a shaped object, for example a helmet made by injection molding from polyurethane. The pattern can be an ornamental design, a logo and the like. 
     In another aspect, the invention provides a method of manufacturing protective headwear, for example a helmet, by placing a patterned cover sheet in first molding die to shape the cover sheet in the shape of the die. A reflective sheet is placed on the shaped patterned cover sheet and molding material is injected between the reflective sheet and a second molding die to form the shaped object. The reflective sheet is thereby sealed between the cover sheet and the molded shaped object. 
     In another aspect of the invention, a method of manufacturing light-reflecting objects includes first forming a shaped object and then covering the shaped object, in succession, with a reflective sheet and a patterned cover sheet. 
     Embodiments of these methods may include one or more of the following features. The reflective sheet is sealed between the shaped object and the cover sheet, for example, by applying heat and pressure between the shaped object and the cover sheet. The pattern is defined by areas that are transparent to the optical radiation passing through the cover sheet and by other areas that are opaque to the optical radiation. The pattern can also be defined by a separate patterned sheet placed between the cover sheet and the reflective sheet. The light-reflecting object can be a molded helmet that is preferably made of polyurethane. 
     Additional features and advantages of the present invention will be apparent from the following description of preferred embodiments and from the claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows an embodiment of the reflective object according to the invention; 
     FIG. 2 shows another embodiment of the reflective object according to the invention; 
     FIGS. 3A to  3 C show examples of applications for the reflective objects; 
     FIG. 4 shows another embodiment of the reflective object with a lateral seal; 
     FIGS. 5 and 6 show other embodiments of the reflective object; and 
     FIGS. 7 and 8 are flow diagrams of methods for producing the reflective object. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the drawings, identical elements or elements performing identical functions are indicated with identical reference numerals. 
     Referring to FIG. 1, a reflective object  10  includes a base  12  that is made of a material impervious to moisture, such as metal or plastic and preferably polyurethane. The base  12  can be rigid or flexible. Overlaying the base  12  are, in succession, a reflective sheet  13 , a patterned sheet  14  and a transparent cover sheet  19 . The cover sheet  19  is preferably made of a plastic material that is essentially impervious to air and moisture. The reflective sheet  13  includes a plastic sheet coated with a highly reflective metal, such as aluminum, silver or gold, or other suitable material with a high index of refraction. The patterned sheet  14  need not be a separate sheet, but can be printed on or embossed onto the transparent cover sheet  19 . The patterned sheet  14  includes areas  18  that are opaque to light passing through the transparent cover sheet  19 , and areas  16  that are transparent to the light. The transparent areas  16  and opaque areas  18 , in aggregate, form a desired pattern or design. The opaque areas and the transparent areas can be colored, i.e., the areas can reflect and/or transmit selected spectral ranges of the light striking the surface of the object. 
     When light  15 ,  17  passes through the transparent cover sheet  19 , the opaque areas  18  of patterned sheet  14  prevent a portion of the light  17  from reaching the reflective sheet  13 , so that little, if any, light is reflected. On the other hand, light  15  that passes through the transparent areas  16  of the patterned sheet  14  and reaches the reflective sheet  13 , is reflected by the reflective sheet  13 . As a result, from the perspective of a viewer facing the transparent cover sheet  19 , the opaque areas  18  appear dark, whereas the transparent areas  16  reflect the light and appear bright. In other words, the viewer sees a pattern having a shape that is defined by the shape of the transparent areas  16 . 
     Referring now to FIG. 2, in another embodiment of the invention, the reflective object is a shaped object, e.g., a molded object  22 , such as a molded helmet, a sculptured sign and the like. The shaped object is preferably made from a material that is impervious to air and moisture. 
     Referring to FIGS. 3A to  3 C, illustrative examples of various reflective objects having base  10  or shaped base  31  of FIG. 1A and 1B are shown. FIG. 3A shows a warning sign  30  with reflective lettering and/or a reflective background. In this embodiment, the base  12 , the reflective sheet  13 , the patterned sheet  14 , and the transparent cover sheet  19  are preferably sealed along the lateral edges  42 , as also illustrated more particularly in FIG.  4 . This design prevents air and moisture from the environment from reaching the reflective sheet  13 . 
     Referring to FIGS. 3B and 3C, a reflective object is a protective helmet  32 , for example a safety helmet (e.g., a bicycle or motorcycle helmet or a construction helmet) is shown. The reflective pattern applied to the helmet  32  can have the form of an ornamental design  34  (FIG. 3B) or a descriptive label and/or a logo  36  (FIG.  3 C). The helmet  32  can be produced, for example, by an injection molding process, as described below. 
     As seen in FIG. 4, the reflective sheet  13  can advantageously be hermetically sealed against the environment with a seam  42 . For example, a molding machine or a sealing press (not shown) can apply pressure and/or heat between the cover sheet and the base along predetermined seams  42  to encapsulate the reflective sheet between the base and the cover sheet. In this way, large sheets with several objects  32  can be manufactured on a base  12  in a single manufacturing process. The sheets are then cut along the seams  42  to separate the individual objects which are now sealed along their respective marginal edges. Alternatively, the base  12  and the shaped object  22 , respectively, and the reflective sheet  13  can also be sealed between the cover sheet  19  and the base  12  or the shaped object  22  by applying heat and/or pressure over the surface area of the base or the shaped object and  19 . 
     Referring now to FIG. 5, in another embodiment, a reflective object  50  includes a reflective sheet  52  in the form of a multilayer dielectric stack. In this case, the reflective sheet  52  is formed of a sequence of thin alternating dielectric layers  131 ,  132 , wherein consecutive layers have a different index of refraction. When a dielectric stack  52  of this type is illuminated, the stack  52  selectively reflects one or more colors of the light. The color depends on the thickness and the index of refraction of the thin sheets and on their arrangement with respect to each other, as is known in the art. The specific color or colors can also depend on the direction from which the object is viewed. A dielectric stack  52  can have a significantly higher reflectivity than a single reflective sheet  13 . The reflective sheet  52  can also include holograms (not shown). 
     Referring now to FIG. 6, a reflective object  60  can be designed to reflect more than one color of the light striking the object. For example, when the thickness and refractive index of the thin layers  131 ,  132  are properly dimensioned, the dielectric stack  52  can be designed to reflect, for example, the red and blue spectral range of the light. Since the red and blue reflected colors add to form a green color, the transparent areas  64  appear green while the opaque areas  62  appear dark, as described above. However, the optical properties of the patterned sheet  14  and/or of the transparent cover sheet  19  can also be made color-selective, i.e., these sheets can function as optical filters. For example, the areas  62  of sheet  14  can be designed to absorb the red portion of the light and will therefore transmit only the blue portion of the red and blue light reflected by the dielectric stack  52 . The areas  62  will therefore appear blue in reflection. Likewise, the areas  64  of sheet  14  can be designed to absorb the blue portion of the reflected light and will therefore transmit only the red portion of the light. The areas  64  will therefore appear blue in reflection. The cover sheet  19  can also have a spectrally selective light transmission. In other words, the reflective sheet  52 , the patterned sheet  14  and cover sheet  19  can be designed to have different optical properties. Consequently, these sheets can be combined to produce a variety of different colors. The invention can therefore provide colorful reflective objects that can be produced in a simple manner. 
     Referring now to FIG. 7, a process  70  for manufacturing a molded shaped object  20  (FIG. 2) with a reflective pattern is described. A printed pattern of desired shape and color is applied to a transparent cover sheet  19 , step  72 . Alternatively, as described above, instead of applying the pattern directly to the cover sheet  19 , a patterned sheet  14  can be placed on the cover sheet  19 . The transparent cover sheet  19  and the patterned sheet  14  are then placed in a first molding die (not shown), with the pattern or the patterned sheet  14  facing away from the molding die, step  73 . The combination formed by the cover sheet  19  and the patterned sheet  14  is then molded to conform to the shape of the molding die, using high temperature and vacuum techniques, step  74 . The reflective sheet  13 ,  52  is placed on top of the molded patterned sheet  14 , step  75 , and a plastic molding material, e.g., polyurethane, is injected between a second molding die (not shown) and the reflective sheet  13 , step  76 . The shaped object is formed by applying heat and pressure to the mold, step  77 . The reflective shaped object  20 , e.g., the helmet  32 , which now includes the reflective pattern on its outer surface, is removed from the mold, step  78 . 
     Referring now to FIG. 8, in an alternate process  80 , a shaped object  22 ,  32  is initially formed in a molding machine (not shown), step  82 . The shaped object  22 ,  32  is then covered with, in that order, the reflective sheet  13 ,  52  and the patterned cover sheet  19 , step  84 . As mentioned above, instead of forming a pattern on the cover sheet  19 , a separate patterned sheet  14  can be inserted between the cover sheet  19  and the reflective sheet  13 ,  52 . The reflective sheet  13  is then sealed between the cover sheet  19  and the shaped object  22 ,  32  to protect the reflective sheet  13  against the environment, step  86 . 
     It is to be understood that the embodiments and variations shown and described above are illustrative of the principles of this invention only and that various modifications may be implemented by those skilled in the art without departing from the scope and spirit of the invention.