Abstract:
An extruded housing using a single polymeric material to form an opaque body portion that defines an open channel, a light transmitting lens portion, and a hinge portion joining the body portion to the lens portion to form a unitary body. The hinge portion allows the lens portion to pivot relative to the body portion between an open position, where the channel is open, and a closed position, wherein the lens closes the open channel. The extruded housing is designed to form part of a light emitting diode light fixture, where the housing accepts a strip or plurality of LEDs within the channel for emission of light through the lens portion.

Description:
FIELD OF INVENTION 
       [0001]    This disclosure relates to extruded profiles, particularly extruded profiles for housing strips of light emitting diodes. 
       BACKGROUND AND SUMMARY 
       [0002]    Through the process of extrusion, a vast array of products made from a vast array of materials can be manufactured to have a consistent cross section. To form an extrusion, material is pressed or drawn through a die of a predetermined profile. One material that is commonly extruded is aluminum. The aluminum is heated to approximately 500 degrees centigrade, softening the material. It is then run though the die and allowed to cool. The extrusion process produces an end product that can be cut to any desired length needed for the finished product, including being customized to the customer. 
         [0003]    Extruded aluminum profiles have been used to house strips of light emitting diodes. The profiles may be mounted to a desired surface or recessed into channels formed on the mounting substrate. The extruded aluminum profiles form open channels in which the light emitting diode strips are inserted. The aluminum profiles then require a separate lens to be positioned to cover the open end of the profile&#39;s channel. Most often, these lenses are slid into the extrusion along the length thereof. The lenses have also been designed to snap into these aluminum extrusions without having to be slid along the length of the aluminum extrusion. 
         [0004]    The inventors have determined a number of problems associated with the manufacture of LED fixtures having aluminum extruded profiles fitted with separate lenses. First, the slide-in lenses severely limit the ability to maintain the light fixtures. Most often, the extrusions are cut or selected to be substantially the same length as their supporting surface. As a result, impediments exist, such as the side walls of a cabinet, which would prevent the lens from being removed, without fully disengaging the extruded housing from the support surface. 
         [0005]    Second, extruded aluminum does not possess the necessary light transmission properties to act as a lens for the fixture. Therefore alternative materials must be used, often times various polymers. The use of polymer for the lens, while the profile housing is made from aluminum, causes manufacturing issues. The material of the lens and the material of the housing portion have different levels of warp, different degrees of expansion and contraction/shrinkage when the extruded material is cooled. Often, the aluminum extrusion will be sourced to one supplier while the polymer extrusion is sourced to a second supplier. As a result, it can be difficult to provide the lenses and the housings with sufficiently similar dimensional tolerances. Therefore, the lenses will often be of insufficient size to properly couple with the housing. This leads to lenses which are either too large to be properly inserted or too small, having them fall into the channel of the aluminum extrusion. Even if the lens includes a lip portion to prevent falling into the channel, a lens that is too small will be unable to properly engage the inside of the channel. 
         [0006]    Third, aluminum is being a more and more expensive material. This is especially true of aluminum products formed outside of the United States, because tariffs have been placed upon the importation of these products. 
         [0007]    As a result of these problems, the inventors have created an improved extruded housing for strips of light emitting diodes (LEDs). The improved housing uses a single polymeric material for the entire housing, both a channel portion and a lens portion. The channel and lens portions are preferably formed of high density polyethylene polymer. The channel portion and the lens portion are co-extruded to provide a unitary housing where the lens portion is formed with the trough portion in a hinged relationship. This hinged connection, referred to as a “living hinge,” allows the lens to be removably coupled across the open side of the trough, providing selective access to the trough for installation or removable of an LED strip positioned therein. Preferably the co-extrusion of the housing includes a first pigment added to the lens portion to provide a diffusive translucent cover capable of emitting light. Preferably, the co-extrusion of the housing includes a second, different pigment added to the material forming the trough portion to form an opaque region, preferably similar in finish to aluminum. 
         [0008]    These and other aspects of the present invention will become apparent to those skilled in the art after a reading of the following description of the preferred embodiments, when considered in conjunction with the drawings. It should be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The foregoing and still other objects and advantages of the present invention will be more apparent from the following detailed explanation of embodiments of the invention in connection with the accompanying drawings. 
           [0010]      FIG. 1  is a perspective view of a light fixture according to a one aspect of the present disclosure. 
           [0011]      FIG. 2  is an exploded view of the light fixture of  FIG. 1 . 
           [0012]      FIG. 3  is a cross sectional view of a first exemplary extruded housing in a closed position. 
           [0013]      FIG. 4  is a cross sectional view of the first exemplary extruded housing in an open position. 
           [0014]      FIG. 5  is a cross sectional view of a second exemplary extruded housing. 
           [0015]      FIG. 6  is a cross sectional view of a third exemplary extruded housing. 
           [0016]      FIG. 7  is a cross sectional view of a fourth exemplary extruded housing. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    Exemplary embodiments of this disclosure are described below and illustrated in the accompanying figures, in which like numerals refer to like parts throughout the several views. The embodiments described provide examples and should not be interpreted as limiting the scope of the invention. Other embodiments, and modifications and improvements of the described embodiments, will occur to those skilled in the art and all such other embodiments, modifications and improvements are within the scope of the present invention. Features from one embodiment or aspect may be combined with features from any other embodiment or aspect in any appropriate combination. For example, any individual or collective features of method aspects or embodiments may be applied to apparatus, product or component aspects or embodiments and vice versa. 
         [0018]    Turning to  FIGS. 1 and 2 , a light fixture  1 , and exploded view thereof ( FIG. 2 ), having an extruded housing  2  according to this disclosure, is shown. The light fixture  1 , includes an extruded housing  2  configured to contain a strip of light emitting diodes (LED)  4 . Although LEDs are preferred, alternative emitters of light are contemplated, including organic light emitting diodes (OLED) and electroluminescent (EL) wires or panels. Alternative sources of light within the extruded housing  2  may also include indirect emitters of light such as edge lit light guides or optical fibers. 
         [0019]    The LED strip  4  preferably includes a segment of flexible LED ribbon. For example model 3015 LED ribbon available from Hafele America. The flexible LED ribbon of this type includes a flexible substrate  41  with LEDs  44  disposed on one surface of the substrate, and an adhesive disposed on the opposite side of the substrate. The adhesive on the substrate  41  allows the LED strip  4  to be held in place once positioned within the extruded housing  2 . The ribbon is formed with predetermined break points disposed between the LEDs so that any length of LED ribbon can be selected and used to form the LED strip  4  of the light fixture  1 . The LED strip  4  can include alternative structures resulting in a plurality of LEDs arranged in a linear pattern for placement within the extruded housing  2 . For example, a predetermined number of LEDs may be disposed along a predetermined length of a substantially rigid circuit board. 
         [0020]    The light fixture  1 , further comprises an end cap  6  inserted into each opposite end of the extruded housing  2 . The end caps  6  comprise a body  61  forming an end face for the light fixture  1 . Extending inwardly from the body  61  is a pair of L-shaped projections  63 . The L-shaped projections  63  are configured to form a friction fit with the interior surface of the extruded housing  2 . Preferably, at least one of the end caps  6  will include an opening  65 . The opening  65  provides access to the interior of the housing for connector cord  97  in order to power the LED strip  4 . 
         [0021]    As seen in  FIGS. 1 and 2 , the light fixture  1 , may further comprise electrical components  9  in order to operate the LEDs  44  of the LED strip  4 . The electrical components  9  may include a driver assembly  91  to provide the LED strip with the necessary voltage and current input. The electrical components  9  may further include a switch  93  to be operated by the user. The switch  93  may be integral with driver assembly  91 , may connect to the driver assembly  91  by a wired connection or a remote connection. The electrical components  9  may further include a power cord  95 . The power cord  95  attached, integrally or removably, to the driver assembly  91  to provide access to an external power source such as a wall socket. The driver  91  may alternatively receive power from: a battery source, such as lithium or alkaline; a renewable source, such as connected to a photovoltaic cell; or be directly wired to a buildings power supply. 
         [0022]    The electrical components  9  will also likely include at least one connector cord  97 . The connector cord  97  having at least one electrical connector  98  for connection to the LED strip  4 . The connector cord may then be passed through opening  65  in one of the end caps  6  for connection, direct or indirect, integral or removable, with the driver assembly  91 . 
         [0023]    Turning to  FIGS. 3 and 4 , a cross section of a first exemplary extruded housing  2  is shown.  FIG. 3  shows the extruded housing  2  in a closed position, while  FIG. 4  shows the extruded housing  2  in an open position. The extruded housing  2  includes a trough portion  21 . The trough portion  21  includes a bottom wall  211  and two side walls  213  extending upwardly from the opposite edges of the bottom wall  211  to form a U-shaped channel  215 . Each of the walls  211 ,  213  of the trough portion  21  are substantially the same thickness. Having a substantially similar thickness improves predictability in manufacturing since each wall  211 ,  213  will cool evenly, minimizing differences in shrinkage and warp. The walls  211 ,  213  may have a thickness between about 1 mm and about 2 mm, preferably between 1.3 mm and 1.5 mm. The channel  215  should be of sufficient width to accommodate the LED strip  4 . The adhesive of the LED strip  4  may be used to attach the LED strip  4  to the bottom wall  211 . The channel  215  may have a width of at least about 8 mm and preferably between about 13 mm and about 16 mm. These dimensions will allow the channel  215  to closely enclose the LED strip  4 ; however other dimensions may be selected based on the type of light emitting units, area, and brightness of light to be emitted from a light fixture  1  using the extruded housing  2 . For example, the channel  215  may be formed with sufficient width to accommodate a plurality of side-by-side LED strips  4 , thereby increasing the brightness of the assembled fixture  1 . 
         [0024]    Each of the side walls  213  may include a first projection  217  extending into the channel  215  adjacent to the bottom wall  211 . The first projection  217  of each side wall  213  may be capable of being disposed above the substrate  41  of the LED strip  4  and helping maintain the position of the LED strip  4  relative to the housing  2 . Each of the side walls  213  can further include second projection  218 . The second projection  218  extends inwardly toward the channel  215  from the distal end of each side wall  213 , opposite the bottom wall  211 . 
         [0025]    The extruded housing  2 , further comprises a lens portion  24 . The lens portion  24  is disposed across the open end of the U-shaped channel  215  of the trough portion  21  and connected thereto along one edge by a living hinge  27 . The lens portion  24  is adapted to enclose the extruded housing  2  and transmit light emitted from the light source, such as LED strip  4 , disposed within the channel  215 . To improve the ease of manufacturing, the lens portion  24  should have a thickness that is reasonably similar to the thickness of the walls  211 ,  213  of trough portion  21 . The lens portion  24  has a width that is wider than the channel  215  so that at least one area  241  of the lens portion  24  abuts the top of at least one of the side walls  213 . 
         [0026]    The lens portion  24  has an outer surface  242  that may be flat ( FIG. 3 ) or may be convex ( FIG. 5 ). The flat outer surface  242  provides the housing  2  with a lower profile, desired in some applications. The lens portion  24  has an inner surface  243  that may have a generally concave profile. The concaved inner surface  243  may be also be scalloped as shown in  FIG. 3 . The scalloped nature of the inner surface  243  will help to diffuse light passing though the lens portion  24 . Because LEDs  44  are bright points of light, the diffusion of the light will provide a pleasing uniform illumination emitted from the light fixture  1 . 
         [0027]    The lens portion  24  further includes at least one locking arm  244  extending from the inner surface  243 . The locking arm  244  includes a protrusion  245  that extends from an end of the at least one locking arm  244  in an outward direction. The protrusion  245  of the locking arm  244  is configured to engage a lower surface of second projection  218 . The at least one locking arm  244  is sufficiently resilient to form a snap fit with the second projection  218 , thereby holding the lens portion  24  in place relative to the trough portion  21 . 
         [0028]    The extruded housing  2  can further include a hinge portion  27 . The hinge portion  27  comprises an area of reduced thickness integrally connecting the top distal end of one of the side walls  213  of the trough portion  21  to a distal end of the lens portion  24 . The hinged portion  27 , commonly called a “living hinge,” maintains the connection between the lens  24  and the trough  21 , but allows the lens  24  to pivot relative to the trough  21 , thereby allowing access to channel  215 . Access to the channel  215  is important for maintaining or replacing the LED strip  4  to be disposed within the channel  215 . Due to the hinged access, the fixture can be assembled before or after the extruded housing  2  is joined to its support surface. The hinged portion  27  eliminates the need to slide out the lens  24 , minimizing the space needed to access the channel  215 . The hinged portion  27  also prevents loss of the lens  24  and minimizes the potential for damage to the lens  24  which could occur if the lens  24  were placed apart from the trough  21 . 
         [0029]    As discussed above, the hinge portion  27  connects one side of the trough  21  to one side of the lens  24 . To connect the opposite sides of the trough  21  and lens  24 , the at least one locking arm  244  engages with the bottom of the second projection  218 . 
         [0030]    All elements of the extruded housing  2  are co-extruded using a polymeric material. Preferably, the trough  21 , lens  24 , and hinge  27  combine to form a unitary polymeric extrusion. While generally, the trough  21 , lens  24 , and living hinge portion  27  will be preferably formed from the same polymer, it is also possible to use different polymers for the different portions. By using only a single polymer, however, the extrusion process renders much more consistent results, providing a match fit every time. Comparatively, extrusion of a plurality of different materials can result in differences in melting point, warp, shrinkage and the like, all of which hinder the ability to manufacture the housing  2  to consistent specifications. 
         [0031]    The extruded housing is preferably made using high density polyethylene (HDPE). Other polymers may also be used, including high temperature ABS, acrylic or polycarbonate. Extruding the housing  2  using a polymeric material also provides an electrical insulator, thereby eliminating the need for a separate insulator between the trough and the light source, used in the prior art aluminum extrusions to prevent the potential for capacitive coupling. 
         [0032]    In a preferred embodiment, various pigments will be added to the base polymer during extrusion. A first pigment may be added to the portion of the polymer forming the lens portion  24  or forming the lens portion  24  and the hinge portion  27 . The first pigment will provide the respective portions with a milky white, translucent color. The first pigment may be a UV inhibitor. The resulting milky white will provide a pleasing appearance to the light fixture  1  because it will mask the contents of the housing  2  when the light fixture is off, and will diffuse the light from the LEDs  44  when the light fixture is turned on. 
         [0033]    In a preferred embodiment, a second pigment may be added to the portion of the polymer forming the trough portion  21 . The second pigment will render the trough portion  21  opaque. An opaque trough portion  21  will prevent loss of light through the housing  2  in undesired locations. In one embodiment, the second pigment may be a conventional colorant. Use of a gray colorant will provide the trough portion with a metallic appearance, designed to simulate the aluminum troughs of the prior art. 
         [0034]      FIGS. 3 and 4  show a cross section of the first exemplary embodiment of the extruded housing  2  configured to be inlaid with respect to a support surface. In this first embodiment, each of the side walls  213  may include a set of third projections  225  extending from the exterior surface of each wall  213 . The third projections  225  are used to increase the friction fit between the housing  2  and a groove in the support surface in which the housing  2  will be inlaid. The extruded housing  2  of this first exemplary embodiment further comprises a flange  227  extending outwardly from the distal ends, opposite the bottom wall  211 , of the side walls  213 . The flange  227  provides a finished appearance when the housing  2  is inlaid within the support surface, preventing over insertion, and providing a decorative border region of the preferred metallic appearance. 
         [0035]      FIG. 5  shows the cross section of an extruded housing  2 ′ according to a second exemplary embodiment of the present disclosure. The extruded housing  2 ′ may be fitted with all of the components of the light fixture  1  found in  FIGS. 1 and 2 . The extruded housing  2 ′ of this embodiment is intended for use on a support surface without being inlaid into a groove. In order to attach the extruded housing  2 ′ to a support surface, adhesive may be disposed along the bottom of bottom wall  211 . The lens portion  24  and hinge portion  27  may combine to form a width similar to equal to the outer dimension of trough portion  21  to minimize the appearance of the trough portion  21  when viewing the fixture from a direction perpendicular to the lens portion  24 . 
         [0036]      FIG. 6  shows the cross section of an extruded housing  2 ″ according to a third exemplary embodiment of the present disclosure. The extruded housing  2 ″ of this third embodiment comprises side walls  213  that extend outwardly from the bottom wall  211  at an oblique angle. Preferably each side wall  213  extends from the bottom wall  211  at an angle of forty-five degrees, thereby forming a right angle between the two side walls  213 . This right angle arrangement allows for the extruded housing  2 ″, and any fixture  1  formed therefrom, to be mounted at the interior corner formed by two housing support surfaces. In this embodiment, each of the side walls  213  may have adhesive disposed thereon for attachment to the housing support surfaces. Likewise, the arrangement of the housing  2 ″ results in the bottom wall  211 , or an additional LED strip supporting wall  230  disposed parallel thereto, to be angled relative to the housing support surfaces. This provides improved directional lighting into the spaced defined by the housing support surfaces. 
         [0037]    Referring to  FIG. 7 , an additional embodiment of the present invention is shown. The extruded housing  2 ′″ is substantially similar to the extruded housing of  FIGS. 3 and 4 . Extruded housing  2 ′″ is distinct in that each of the side walls  213  include a fourth projection  219  disposed below each second projection  218  to form a recess  220 . Further, the lens portion  24  includes an additional locking arm  244  and protrusion  245  on the hinge side of the housing  2 ′″. The additional locking arm  244  engaging the recess  220  between second projection  218 , and the fourth projection  219 . Although not shown with additional figures, the elements added to the first housing embodiment  2  to achieve housing  2 ′″ can also be added to housings  2 ′ (FIG.  5 ) and  2 ″ ( FIG. 6 ). 
         [0038]    Although the above disclosure has been presented in the context of exemplary embodiments, it is to be understood that modifications and variations may be utilized without departing from the spirit and scope of the invention, as those skilled in the art will readily understand. Such modifications and variations are considered to be within the purview and scope of the appended claims and their equivalents.