Abstract:
The present invention is directed toward a cover for an illumination device including a composite image including selectively visible design elements. The exterior surface of the cover may include a design element viewable regardless of whether the light source is extinguished or illuminated. The interior surface of the cover may further include a design element that is viewable on the exterior surface only when the light source is illuminated. Thus, when a viewer views the exterior of the lamp generally in elevation, the cover selectively displays different designs to the viewer depending on the illumination state of the device.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Patent Application No. 60/976,540 filed 1 Oct. 2007 and entitled “Cover for a Luminary Device and Method of Forming”, the disclosure of which is hereby incorporated by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to covers for luminary devices having selectively-viewable composite image portions and, in particular, to lampshades configured to selectively display image portions to a viewer. 
     BACKGROUND OF THE INVENTION 
     Lamps and their corresponding lampshades are well known and widely used in a variety of settings. For example, lamps can be used to provide all of the lighting requirements in a specified area, to supplement overhead lighting or as a decorative element within a room. Lamps are available in a wide variety of configurations including floor lamps, desk lamps and many alternative configurations. A typical lamp assembly includes a base member, an electrical assembly (including a switch and bulb assembly), and a lampshade. 
     Lampshades provide the overall visual appearance of a lamp assembly. Lamps and lampshades are often specifically selected for use due to their overall visual appearance as opposed to operation characteristics. As such, lampshades are available in a wide variety of different styles that can make use of differing materials of construction as well as differing shapes and sizes. In addition, lampshades can be selected to have desired colors and patterns. In some instances, lampshades can be selected that include hand-painted scenes or pictures along its exterior (viewing) side. 
     Thus, lampshades serve as important ornamental details in a room or home interior design. Manufacturers offer lampshades in a wide variety of materials and designs. Nevertheless, there is always a need for an improved lampshade that has unique visual appeal and can be produced in a wide variety of ornamental designs. 
     SUMMARY OF THE INVENTION 
     The present invention is directed toward a cover for a luminary device including a selectively visible image portions. The cover may be in the form of a lampshade including a body with an exterior surface and an interior surface. The exterior surface may include a design element viewable regardless of whether the light source is extinguished or illuminated. The interior surface may further include a design element that may be viewable on the exterior surface only when the light source is illuminated. In operation, when viewing the exterior surface of the lamp, a viewer sees only a portion of the complete image when the light source is extinguished (i.e., only the exterior design element). When the light source is illuminated, however, the viewer sees a complete image on the exterior surface (i.e., a composite image including both the interior and exterior design elements). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  illustrates a top perspective view of a cover for a luminary device in accordance with an embodiment of the invention. 
         FIG. 1B  illustrates a bottom perspective view of the cover of  FIG. 1A , showing the interior design element. 
         FIG. 2  illustrates a cross-sectional view of the cover of  FIG. 1A . 
         FIG. 3  illustrates a close-up of the exterior surface of the cover of  FIG. 1A , showing a protruding design element. 
         FIG. 4A  is a perspective view of a lamp assembly including the cover of  FIG. 1A , with the light source in an extinguished state and showing the interior design element in phantom. 
         FIG. 4B  is a perspective view of the lamp assembly of  FIG. 4A , with the light source in an illuminated state and showing the composite image. 
     
    
    
     Like reference numerals have been used to identify like elements throughout this disclosure. 
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1A  illustrates a top perspective view of a cover for a luminary device in accordance with an embodiment of the invention, while  FIG. 1B  illustrates a bottom perspective view. As shown, the cover  10  may be in the form of a lampshade including a body  100  defining an interior channel having a lower end or rim  105  and an upper end or rim  107 . In the embodiment illustrated, the lower end  105  is opened and the upper end  107  is closed. That is, the upper end  107  includes a cap  108  with an aperture to permit the escape of heat and/or to provide an insertion point for a supporting and/or electrical cord. It should be understood, however, that both ends  105 ,  107  may be closed or opened. The body  100  may possess a unitary (one-piece) structure having a substantially consistent thickness throughout. 
     The body  100  further possesses a first or exterior surface  110  and a second or interior surface  120 .  FIG. 2  illustrates a cross-sectional view of an illuminating device  200  (e.g., a lamp assembly) including a light source  210  and the cover  10  of  FIG. 1A . As shown, the exterior surface  110  is oriented toward a viewer V of the lampshade, while the interior surface  120  is oriented toward the light source  210  (e.g., a light bulb). The exterior surface  110  includes a first or exterior design element  130 . The interior surface  120 , similarly, includes a second or interior design element  140 . 
     Each portion of the cover  10 —the body  100 , the exterior design element  130 , the interior design element  140 —are configured to possess predetermined light transmission properties. That is, each portion  100 ,  130 ,  140  allows a predetermined percentage of incident light to pass through the cover  10  to enable the selective display of the design elements  130 ,  140  to a viewer viewing the exterior surface  110  of the body  100 . By way of example, the exterior design element  130  and the interior design element  140  may possess one light transmission value, while the body  100  (i.e., the portions of the body not including the design elements) may possess a different light transmission value. By way of further example, the exterior design element  130 , the interior design element  140 , and the body  100  may each possess different light transmission values (e.g., when viewed from the outside of the lamp). 
     In one embodiment, each portion  100 ,  130 ,  140  possesses a predetermined thickness value configured to provide the desired light transmission values. That is, each design element  130 ,  140  either protrudes from or is recessed into the surfaces  110 ,  120  of the body  100  to create areas of varying thickness along the body.  FIG. 3  is a close-up view of the exterior design element  130  in accordance with an embodiment of the invention. As shown, the exterior design element  130  may be defined by a raised area or rib (also called a protrusion) extending from the exterior surface of the body  100 . Also, as shown, the rib may be integral with the body  100  (creating a cover having a unitary structure). Similarly, the interior design element  140  may be defined by a raised area or rib extending from the interior surface  120  of the body  100 . 
     While ribs are illustrated, it should be understood that the design elements  130 ,  140  may be defined by a recess or groove formed into the surfaces  110 ,  120  of the body  100  (not illustrated). 
     As noted above, the relative thicknesses of the design elements  130 ,  140  and the body  100  may be selected to provide the desired light transmission values. By way of example, when the thickness of the body  100  is about 1 mm, the thickness of each protruding design element  130 ,  140  may also be about 1 mm (thus the thickness of an area of the cover  10  including the design element is about 2 mm, while the remaining (normal) portions of the body are about 1 mm). By way of further example, when the thickness of the body  100  is about 3 mm, the thickness of each protruding design element  130 ,  140  may also be about 3 mm (thus the thickness of an area of the cover  10  including the design element is 6 mm). Thus, the ratio of thicknesses of the body  100  including a protruding design element  130 ,  140  with respect to the normal thickness of the body  100  (i.e., the thickness not including the design elements) may be about 2:1. 
     When a recess or groove forms the design element  130 ,  140 , the ratio of thickness of the recessed design element  130 ,  140  with respect to the normal body portion (i.e., the portion of the body  100  not including the design) may be about 1:2. That is, the depth of recessed design element  130 ,  140  is no more than half the normal thickness of the body  100 . Any recessed design elements are configured such that none extend completely though the body  100  (i.e., apertures do not define any feature of the design elements). 
     Stated another way, the thickness value T 1  of the body  100  measured at a point including an exterior design element  130  differs from the thickness value T 2  of a normal body portion, i.e., the body  100  at a point not including the exterior design element  130 . This variation in thickness alters the light transmission properties of the body  100 . As a result, the body  100  at thickness T 1  transmits light at a first transmission value, while the body  100  at thickness T 2  transmits light at a second transmission value, which is different from the first transmission value. Similarly, the thickness value T 3  of the body  100  measured at a point including an interior design element  130  differs from the thickness value T 2  of a normal body portion. As such, it possesses a third light transmission value. In this manner, the design elements  130 ,  140  possess a different light transmission value from the normal body area. 
     The material forming the cover may be any material capable of transmitting light from the light source in predetermined amounts, and may be formed from material that is transparent, semitransparent, or translucent. For example, the material may include, but is not limited to, glass, plastic, etc. For example, the plastic material may be a thermoplastic resin including, but not limited to acrylonitrile butadiene styrene; polyvinyl chloride; polypropylene (e.g., polypropylene, talc-filled polypropylene, calcium filled polypropylene, and polypropylene copolymers); polyethylene (low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), high-density polyethylene (HDPE), ultra high molecular weight polyethylene (UHMWPE)); polyamide, polyester; and polycarbonate. 
     The cover  10  may be formed utilizing processes that produce a seamless, unitary body  100  including the design elements  130 ,  140 . For example, molding techniques such as injection molding, co-injection molding, profile extrusion, ram extrusion, injection molding, co-injection molding, and blow molding may be utilized. By way of further example, the cover  10  may also be formed utilizing processes such as glass blowing, molding, etc. In the glass molding process, a mold is created with the negative of the design elements  130 ,  140  etched or embossed into the mold. Glass is poured into the mold and hardens with both designs  130 ,  140  being a permanent, integral part of the structure. In the glass blowing process, a body  100  of glass is formed, and the design  130 ,  140  is etched into the glass (i.e., the etching step takes place after the body of the cover is formed). Alternatively, to create a raised design, molten glass could be placed on the surface of the body and allowed to harden (i.e., the design is created separately, yet applied while the glass is still warm so that the final structure is again a unitary structure with a permanent design). 
     By way of still further example, the cover  10  may also be formed via a computer controlled cutting or building process such as machines using computer numerical control (CNC), and selective laser sintering (SLS), and/or stereolithography (SLA). In a selective laser sintering (SLS) process, a CO 2  laser sinters (fuses) a powder material (e.g., nylon or other material), with the laser tracing an object&#39;s cross sectional geometry layer by layer. 
     Stereolithography is a 3D laser printing technique that produces 3D objects by hardening (polymerizing) a photosensitive epoxy resin. Stereolithography uses a vat of liquid, UV-curable photopolymer resin and a UV laser to build parts a layer at a time. On each layer, the laser beam traces a part cross-section pattern on the surface of the liquid resin. Exposure to the UV laser light cures the pattern traced on the resin, adhering it to the layer below. 
     Furthermore, three dimensional inkjet printing may be utilized. In 3D inkjet printing, layers of a fine powder (e.g., resins) are selectively bonded by “printing” a water-based adhesive from the inkjet print head in the shape of each cross-section as determined by a computer aided design file. 
     With this configuration, the body  100  possesses a unitary, seamless structure having sufficient structural support and heat resistant characteristics. The resulting lampshade, moreover, is configured to selectively display a composite image of individual design elements to a viewer of the lamp assembly. That is, the lampshade operates in a first mode, in which only the exterior design element  130  is viewable on the exterior surface  110  of the body, and a second mode, in which a composite image including both the exterior design element  130  and the interior design element  140  are viewable on the exterior surface  100 . 
     The operation of the cover is explained with reference to  FIGS. 4A and 4B .  FIG. 4A  illustrates a lamp assembly  200  including a cover  10  with an exterior design element  130  and an interior design element  140  (shown in phantom in  FIG. 4A ). The light source  210  is extinguished; consequently, the interior design element is not visible to the viewer. That is, the when light source is extinguished, only the first or exterior design element  130  is displayed ( FIG. 4A ) to a viewer of the cover exterior. When the light source is illuminated, however, light is transmitted from the light source  210  and through the body  100 . Due to the varying light transmission properties of the body  100 , the exterior design element  130 , and the interior design element  140 , light is transmitted through the body at varying rates. Consequently, both the exterior design element  130  and the interior design element  140  are visible to a viewer of the cover exterior. 
     With this configuration, portions of a design formed into the cover  10  are selectively displayed to a viewer of the cover exterior. Specifically, when the interior surface  120  of the body  100  is illuminated, the exterior  130  and interior  140  design elements combine into a single, composite design displayed to a viewer of the cover. This, in turn increases the visual appeal of the lamp, since one design configuration is displayed when the light source is extinguished, but another design configuration is displayed when the light source is illuminated. 
     The cover of the present invention may be mounted on a conventional electric lamp to form a lamp assembly. By way of example, the lamp may include a base that supports a light source. A harp may be attached to the base to support the lampshade assembly over the bulb. By way of further example, the lamp may be a pendant lamp or a sconce (as seen in  FIG. 2 ). 
     While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof. For example, the type of light source is not limited, and includes incandescent, compact fluorescent, LED, and xenon light sources. The body  100  may possess any shape and have any suitable dimensions. While a generally frustaconical shape is illustrated, the cover may possess other shapes such as ovals, polygons, etc. The shape may include a closed end and an open end (as illustrated), or may include open ends. In addition, the cover  10  may have a generally annular shape (being a closed ring) or may be an open ring. The cover  10 , moreover, may be in the form of light covers other than lampshades (e.g., night light covers, flat panel covers, etc.). 
     The material forming the cover  10  include any suitable for the purpose described herein. While a moldable material is preferred, other materials (pulp, cotton, woven webs, and other natural and synthetic materials may be utilized). 
     The exterior design element  130  and interior design element  140  may possess any suitable shape or dimensions for the purposes the described herein. The design elements  130 ,  140  may be engraved or embossed (thus recessed into the surface  110 ,  120  of the body  100 ), or may be built up to extend/protrude from the surface of the body. 
     The design elements  130 ,  140  may be integral with the body  100  (as described), or may be separate components connected to the surfaces  110 ,  120  of the body. The design elements may include any combination of recesses or protrusions formed into or coupled to the body  100 . For example, the cover  10  may include a third design element comprising a groove recessed formed into the interior or exterior surface of the body  100 , the third design element being selectively used in combination with raised exterior  130  and interior  140  design elements. 
     Any method suitable to vary light transmission values may be utilized. While providing predetermined thickness values for of the embossed/protruding design elements  130 ,  140  and the normal body portions of the cover  10  is utilized, any configuration that permits the inside design  130  to show through when illuminated, yet disappear from the outer shade when not illuminated may also be utilized. For example, any configuration operable to form a shadow of the interior design element  140  onto the exterior surface  110  of the body  100  may be utilized. In addition to altering thickness, the density, pigmentation, and/or materials forming the design elements  130 ,  140  and/or the body  100  may be selected to provide the desired light transmission values. 
     The type of images formed by the design elements  130 ,  140  is not particularly limited. The interior  140  and exterior  130  design elements may be individual designs that form a composite image and/or may be portions of a complete image revealed when the luminary device is illuminated. 
     The type of luminary device may include, but is not limited to, desk lamps, floor lamps, pendant lamps, sconces, night lights, etc. 
     Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents. It is to be understood that terms such as “top”, “bottom”, “front”, “rear”, “side”, “height”, “length”, “width”, “upper”, “lower”, “interior”, “exterior”, and the like as may be used herein, merely describe points of reference and do not limit the present invention to any particular orientation or configuration.