Abstract:
A light fixture is provided that includes a plurality of light emitting sources, such as e.g., LEDs, that are arranged along a longitudinal direction. A heat sink provides a support structure for the lights while also assisting with the dissipation of heat. A diffuser covers the light emitting sources and is also supported by the heat sink. One or more optical elements such as e.g., a reflector or internally reflecting lens may be used to help direct light rays from the light emitting sources. Certain features may be added at the ends of the light fixture for mounting upon a surface and/or for further controlling the direction of light rays projecting from the light fixture. The light fixture is suitable for a variety of applications including e.g., the illumination of products displayed on shelving for consumer viewing.

Description:
FIELD OF THE INVENTION 
     The subject matter of the present disclosure relates generally to a light fixture, and more particularly, to a light fixture having multiple light sources arranged in a linear or substantially linear manner. 
     BACKGROUND OF THE INVENTION 
     The illumination of items placed on a shelf or series of shelves presents certain challenges. Depending on the location of the light source, one shelf may block light from illuminating another shelf. Similarly, if a light is placed to one side, large items closest to the light may block light from illuminating other items on the same shelf. 
     Aesthetics can also be a concern particularly when attempting to optimize the positioning of the light source to address the above-mentioned illumination issues. For example, in a commercial setting where the items being displayed are e.g., consumer products, it is desirable to properly illuminate the consumer products without blocking the consumer&#39;s view or detracting from the presentation of the products. Additionally, variables such as the color and intensity of the lighting can be particularly important. 
     The use of light sources such as light emitting diodes, halogen bulbs, and others can present additional issues. For example, certain types of light sources can generate significant amounts of heat. This heat must be properly dissipated to e.g., avoid damaging the light fixture or improperly heating surfaces near the light fixture. If the application involves an environment where moisture may be present, such as e.g., a refrigerated display case, it may also be necessary to protect the light sources and/or associated electronics from exposure to such moisture. 
     Accordingly, a light fixture that can provide light from a linear source—i.e. a source where one or more light sources are aligned substantially along a longitudinal direction—would be particularly useful for certain applications. For example, such an arrangement could be used to provide lighting for items placed along a shelf or series of shelves. Such a light fixture that can also be used to provide e.g., the desired color and intensity of light would also be beneficial. Additionally, such a light fixture that can also be provided with features for varying the direction of the light would also be useful. 
     BRIEF DESCRIPTION OF THE INVENTION 
     The present invention provides a light fixture that includes a plurality of light emitting sources, such as e.g., LEDs, which may be arranged along a longitudinal direction. At least one heat sink provides a support structure for the light emitting sources while also assisting with the dissipation of heat. A diffuser covers the light emitting sources and is also supported by the heat sink. One or more optical elements such as e.g., a reflector or internally reflecting lens, may be used to help direct light rays from the light emitting sources. Certain features may be added at the ends of the light fixture for mounting upon a surface and/or for further controlling the direction of light rays projecting from the light fixture. The light fixture may be suitable for a variety of applications including e.g., the illumination of products displayed on shelving for consumer viewing. Additional aspects and advantages of the invention will be set forth in part in the following description, or may be apparent from the description, or may be learned through practice of the invention. 
     In one exemplary embodiment, the present invention provides a light fixture that includes at least one heat sink defining a longitudinal direction. At least one circuit board is attached to the heat sink. A plurality of light emitting sources are mounted to the at least one circuit board. The light emitting sources are spaced apart from each other and may be arranged along the longitudinal direction. A diffuser extends along the longitudinal direction and is attached to the heat sink. The diffuser covers the light emitting sources. 
     These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which: 
         FIG. 1  provides a perspective view of an exemplary embodiment of a light fixture of the present invention with an exemplary diffuser shown in position. 
         FIG. 2  provides another perspective view of the exemplary embodiment of  FIG. 1  without the exemplary diffuser. 
         FIG. 3  illustrates a perspective view of one end of the exemplary light fixture of  FIG. 1  with certain mounting features shown in place. 
         FIG. 4  is a cross-sectional view of the exemplary embodiment of  FIG. 1  as taken along line  4 - 4  in  FIG. 1 . 
         FIG. 5  is another perspective view of one end of the exemplary light figure of  FIG. 1  with an exemplary mounting feature—i.e. an end cap—shown in place. 
         FIG. 6  illustrates a perspective view of the exemplary end cap of  FIG. 5 . 
         FIG. 7  illustrates a perspective view of one end of another exemplary light fixture where certain mounting features have been removed to reveal interior components of the fixture. 
         FIG. 8  is a close up of a portion of the exemplary light fixture of  FIGS. 1 and 2 . 
         FIG. 9  is a cross-sectional view of a portion of the exemplary light fixture of  FIG. 1 . 
         FIG. 10  illustrates a perspective view of the one end of another exemplary light fixture of the present invention. 
         FIG. 11  is a cross-sectional, end view of another exemplary light fixture of the present invention. 
         FIG. 12  is an end view of an exemplary lens of the present invention while  FIG. 13  is a perspective view of the same. 
     
    
    
     The use of the same or similar reference numerals in the figures indicates the same or similar features. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents. 
       FIGS. 1 and 2  provide a perspective view of an exemplary embodiment of a light fixture  100  of the present invention. A diffuser  102  is shown in position in  FIG. 1  while in  FIG. 2  diffuser  102  has been removed to reveal other components.  FIG. 3  provides close-up view of a first end  104  of fixture  100 . 
     Light fixture  100  includes a heat sink  112  that extends along longitudinal direction L between first end  104  and a second end  106 . Each end  104  and  106  includes a bracket  108  and  110 , respectively. Brackets  108  and  110  may be used to mount fixture  100  to a surface. Apertures  114  in each bracket  108  and  110  may be used along with fasteners for such mounting. Other features may be used for mounting light fixture  100  as well. By way of example, light fixture  100  could be mounted at the top and/or bottom of a refrigerated display case and used to illuminate products on shelves in the case. Light fixture  100  may be used in other applications as well. 
     Fixture  100  includes a plurality of light emitting sources  116  spaced apart from each other and arranged along longitudinal direction L as shown. Each light emitting sources  116  may be e.g., one or more light emitting diodes (LEDs). The density and number of LEDs along longitudinal direction L can be determined based on e.g., the application intended for fixture  100 . As shown in  FIG. 2 , light emitting sources  116  are positioned in a straight-line manner along the longitudinal direction. However, it should be understood that it is within the scope of the present invention for light sources  116  to be arranged in other manners, e.g., arranged longitudinally but not necessarily along a straight-line as shown in  FIG. 2 , or arranged laterally. 
     For this exemplary embodiment, a reflector  118  is provided that also extends along longitudinal direction L. Reflector  118  defines a plurality of cavities (or recesses)  120  that are also spaced apart and positioned along longitudinal direction L. More particularly, each cavity  120  is positioned around or otherwise contains at least one of the light emitting sources  116  and includes one or more light reflecting surfaces  122  and  124  for reflecting light away from light fixture  100 . By way of example, reflector  118  could be constructed from a metallized plastic so as to provide light reflective surfaces  122  and  124 . Light reflected from surfaces  122  and  124  passes through diffuser  102 . For this exemplary embodiment, diffuser  102  is constructed from a material of uniform thickness that helps control e.g., the color and/or distribution of the light. 
       FIG. 4  provides cross-sectional view of first end  104  while  FIG. 5  provides a perspective view of first end  104  with a cap  134  in place. Reflector  118  is mounted to a circuit board such as e.g., a fiberglass reinforced printed circuit board  126 . Reflector  118  can be attached using e.g., fasteners  132 . Other fastening mechanisms may also be used. For example, reflector  118  could be manufactured with pegs that provide an interference fit with holes or openings in circuit board  126 . 
     Circuit board  126  also extends along longitudinal direction L and is attached to heat sink  112 . By way of example, circuit board  126  could be provided with fasteners or pegs that extend into a slot  128  provided by heat sink  112  and positioned at the bottom of circuit board  126 . Heat sink  112  is constructed from one or materials that help dissipate heat created by light emitting sources  116 . Heat sink  112  also provides the structure or frame for light fixture  100 . By way of example, heat sink  112  could be constructed from anodized aluminum. For this exemplary embodiment, heat sink  112  is configured to resist collecting dirt and debris, to be readily cleanable by e.g., wiping, and still have substantial surface area for convective cooling. 
     Ends  104  and  106  each include apertures  130  that are oriented along longitudinal direction L. Apertures  130  are configured for the receipt of fasteners  132  that extend through apertures  143  ( FIG. 6 ) in cap  134  to secure cap  134  onto end  104 . As shown in  FIG. 5 , cap  134  includes a peg  136  that extends along longitudinal direction L. Peg  136  is rotatably received into an aperture  140  defined by bracket  108  as shown in  FIG. 6 . A similar construction is used for a cap (not shown) positioned on second end  106  with bracket  110 . As such, after mounting brackets  108  and  110 , light fixture  100  can be rotated in the direction desired as the pegs at first end  104  and  106  rotate within brackets  108  and  110 . A fastener such as a set screw can be inserted into aperture  138  ( FIG. 3 ) to apply force against peg  136  and fix the rotational position of light fixture  100 . A metal insert can be provided that is either heat-staked, ultra-sonically welded, or molded-in to allow such set screw or thumb screw. 
     Returning to  FIG. 4 , an exemplary technique for mounting diffuser  102  to heat sink  112  is shown. Heat sink  112  includes a pair of grooves  150  and  152  positioned on opposite sides of reflector  118  and the plurality of light emitting sources  116 . Grooves  150  and  152  extend along longitudinal direction L. Diffuser  102  may include a pair of opposing longitudinal edges  154  and  156  that are received in a complementary manner into grooves  150  and  152 . Diffuser  102  provides a spring-like force that urges edges  154  and  156  into grooves  150  and  152  to secure the attachment of diffuser  102 . 
       FIG. 7  illustrates another exemplary technique for mounting diffuser  102  to heat sink  112 . More specifically, for the exemplary embodiment of  FIG. 7 , heat sink  112  includes a pair of ribs  142  and  144  positioned on opposite sides and extending along longitudinal direction L. Ribs  142  and  144  project outwardly or face away from each other as well as light emitting sources  116 . Diffuser  102  includes a pair of grooves  146  and  148  positioned on opposite sides of diffuser  102  and also extending along longitudinal direction L. As shown, ribs  142  and  144  are received in a complementary manner into grooves  146  and  148 , respectively, to secure diffuser  102  into position. 
       FIG. 8  provides a close up of a cavity  120  at first end  104  of light fixture  100 . Cavity  120  includes a first pair of light reflective surfaces  122  positioned in an opposing manner about light emitting source  116 . Cavity  120  also includes a second pair of light reflective surfaces  124  positioned in an opposing manner along with the first pair of light reflective surfaces  122  about light emitting source  116 .  FIG. 9  provides a cross-sectional view of light fixture  100  taken along a plane parallel to circuit board  126  and at a position above light emitting source  116 . As shown, the first pair of light reflective surfaces  122  having a first parabolic shape, while the second pair of light reflective surfaces  124  have a second parabolic shape different than the first parabolic shape. The shapes of surfaces  122  and  124  are configured as such to help direct light rays emitted from source  116 . In other exemplary embodiments of light fixture  100 , other shapes may be used for surfaces  122  and  124  in addition to that which is shown including e.g., non-parabolic shapes. 
       FIG. 10  illustrates an end view of another exemplary embodiment of a light fixture  100  of the present invention (mounting features have been removed for purposes of illustrating interior components). Unlike the previously described embodiments, the light fixture  100  shown in  FIG. 10  does not include a reflector. In addition,  FIG. 10  illustrates another exemplary technique for mounting diffuser  102  to heat sink  112 . More specifically, for the exemplary embodiment of  FIG. 7 , heat sink  112  includes a pair of ribs  158  and  160  positioned on opposite sides and extending along longitudinal direction L. Ribs  158  and  160  project inwardly or face towards each other as well as light emitting sources  116 . Diffuser  102  includes a pair of grooves  162  and  164  positioned on opposite sides of diffuser  102  and also extending along longitudinal direction L. As shown, ribs  158  and  160  are received in a complementary manner into grooves  162  and  164 , respectively, to secure diffuser  102  into position. 
       FIG. 11  is a cross-sectional, end view of another exemplary light fixture  100  of the present invention. Unlike previous embodiments, the embodiment of  FIG. 11  includes an optical element or lens  166 . Referring now to  FIGS. 11 ,  12 , and  13 , lens  166  extends along longitudinal direction L and is positioned directly over the plurality of light emitting sources  116 , which are received into a channel  176  defined by the inside surface  178  of lens  166 . By way of example, lens  166  is provided with a pair of projecting inserts  168  and  170  that are received into circuit board  126  to secure lens  166  using an interference fit. Other features may be used to secure lens  166  as well. 
     Lens  166  includes a pair of internally reflecting surfaces  172  and  174 . For this exemplary embodiment, surfaces  172  and  174  may be arcuate in shape (and each may provide an external surface that is convex) within a plane that is orthogonal to longitudinal direction L as shown in  FIG. 12 . As such, some of the light rays from light sources  116  will enter lens  166  through inside surface  178 , reflect off of surfaces  172  and  174 , and exit lens  166  through outer surface  180 . Other shapes for surfaces  172 ,  174 ,  178 , and  180  may also be used in an effort to direct light rays from light emitting sources  116  away from light fixture  100 . By way of example, lens  166  can be manufactured from a polycarbonate or an acrylic material. Lens  166  may be constructed in a variety of lengths to cover one or several light emitting sources  116 . 
     Light fixture  100  can be constructed in a modular manner to help simplify manufacture. For example, referring to  FIG. 2 , a series of modules  182  can be installed on a heat sink  112  that is cut to the desired length. For example, heat sink  112  may be cut to a length of four feet to accept four modules  182 , each constructed at a one foot length. In turn, each module  182  could individually include e.g., a reflector  118  or lens  166 , circuit board  126 , and one or more light emitting sources  116 . Modules  182  can be connected electrically using e.g., connector  184  with wire slots  188  ( FIG. 7 ), mating pin connections  186  ( FIG. 9 ), or other connection mechanisms positioned at the ends of modules  182 . 
     It should be understood that for each exemplary embodiment, diffuser  102  may be constructed with a non-uniform shape and thickness so as to assist in directing light where desired. Additionally, the shape of e.g., diffuser  102  and either reflector  118  or lens  166  can be used together to minimize color separation. For example, lens  166  can be used to focus the light to increase flux density on the target plane while the diffuser  102  can un-focus the light slightly to remove color separation issues. 
     This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.