Abstract:
A scalable design for an LED based cinema light suitable for use in the movie, television, and video industries, among others, is presented. The LED light of the present invention includes a plurality of LED modules arranged in square or rectangular frames or cases. The output of the LED light can be scaled up or down to accommodate any particular need by varying the number of LED modules and types of LEDs used in the light. Each individual LED module features a linear array of LEDs mounted on a base plate, corresponding heat sinks mounted on a back side of the base plate, and a corresponding protective lenses mounted over the LEDs on a front side of the base plate. The LED light of the present invention also features removable lens plate assemblies of focusing lens, wherein the light output of each LED is focused by a corresponding focusing lens.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Application Ser. No. 62/005,519, filed on May 30, 2014, the contents of which are expressly incorporated herein by reference in their entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates generally to high output lights for use principally in the motion picture, television and video industries, and, more particularly, to a design for a high output LED based light suitable for set lighting. 
         [0004]    2. Background of the Invention 
         [0005]    Lighting systems are an integral part of the motion picture, television, and video industries. Proper illumination is necessary when filming motion pictures, television shows, music videos and the like, regardless of whether such activities take place indoors or outdoors. 
         [0006]    Prior art cinema lights typically comprise incandescent, tungsten-halogen or xenon lamp bulbs enclosed within a metal housing which typically includes an assembly for holding the bulb or bulbs, a reflector and a focusing lens. Prior art cinema lights of this type of construction work well and have been developed to provide a beam of projected light of relatively uniform intensity across the entire area of the projected beam. Nevertheless, prior art cinema lights have several drawbacks. In particular, the lights are energy inefficient and generate substantial heat. 
         [0007]    Prior art cinema lamps are notably energy inefficient because in prior art lamps, most of the light generated by the typical omnidirectional incandescent, tungsten-halogen or xenon bulbs, actually strikes and is absorbed by the interior of the housing. Relatively little of the total light generated is directed or reflected forward to serve as useful light. This inefficiency in light projection is compounded by the general inefficiency of incandescent, tungsten-halogen or xenon light bulbs. 
         [0008]    The other major drawback of prior art cinema lights is very high heat production. Due to the heat generated, care must be taken regarding the placement of the lighting fixtures and the manner in which they are handled. The heat generated by prior art cinema lamps also effects the duration of time for which they can be used, as excessive heat production effects bulb life. The heat produced by prior art cinema lamps may also create other drawbacks such as limiting how close subjects can approach the lamps and causing localized distortions in the ambient air which may cause optical distortions apparent on the filmed or recorded image. Color changes in light output may also occur due to the effect of heat aging of the bulb or bulbs. 
         [0009]    In recent years, lights using pluralities of light-emitting diodes or “LEDs” have gained in popularity in applications such as streetlights and outdoor area lights. Now LED based lights are beginning to find application in the movie, television and video production industries. LED based lights have certain advantages over conventional lamps, namely they are relatively bright, relatively energy efficient, have a long life and a consistent color temperature, and while LED lamps generate substantial heat, it is nevertheless less than that generated by prior art cinema lights using incandescent, tungsten-halogen or xenon bulbs. 
         [0010]    The art of LED lamp design, particularly for cinema lighting, is relatively new. At the present time such lights are just beginning to be introduced to the film and television industries and no particular design has proven to be superior and the industry has yet to settle on a standardized design. Many issues related to how best to design LED based lights for use in the film, television and video production industries have yet to be adequately resolved, leaving room for improvement in the art. 
         [0011]    It is the purpose of the present invention to provide a design for an LED based lamp suitable for stage lighting in the movie, television and video production industries. 
       SUMMARY OF THE INVENTION 
       [0012]    The LED cinema light of the present invention presents a scalable design for an LED based cinema light suitable for use in the movie, television, and video production industries, as well as for use in any application where general area lighting is desired. The present invention LED cinema light addresses many of the design issues faced in developing high output area lights for general area lighting applications, as well as movie, television and video applications. 
         [0013]    The present invention LED cinema light includes a plurality of LED modules arranged in square and rectangular frames or cases. The output of the LED cinema light can be scaled up or down to accommodate any particular need by varying the number and length of the LED modules used in the light, as well as the power handling capability of the individual LEDs used in the modules. 
         [0014]    In each LED module, the individual LEDs are mounted as a linear array on a front surface of a base plate, which in the exemplary embodiment is a generally elongated, rectangular aluminum extrusion, upon which a plurality of individual LEDs and associated wiring are attached by means of electrically insulative epoxy. Placed over each individual LED in an LED module, and embedded in the epoxy, is a clear, protective lens, which in the exemplary embodiment is plano-convex dome shaped lens, which both protects the LED and focuses the emitted light. The heat produced by each individual LED is conducted from the LED and dissipated to the atmosphere by means of a heat sink attached behind the LED on a backside of the base plate of the LED module. In alternative embodiments, the heat sink may be fabricated as part of the base plate, i.e. the base plate and heat sink may be a unitary component. 
         [0015]    The LED modules are mounted in the frame or case such that there is a longitudinal air gap between each adjacent LED module and a similar longitudinal air gap between end LED modules and the frame or case. The longitudinal air gaps assist in dissipating the heat generated by the LEDs by allowing air flow past the LED modules through the gaps. The cooling effect contributed by the air gaps is believed to be most significant when the LED Cinema light of the present invention is pointed either straight up or straight down. 
         [0016]    The light produced by each individual LED is also focused by an associated focusing lens, which in the exemplary embodiment, is a refractive lens, centered over each LED and associated protective lens. The individual focusing lenses are mounted to lens plate assemblies in a linear array, where one focusing lens corresponds to one LED in an LED module. Thus, for each LED module in the LED cinema light of the present invention, there is a corresponding lens plate assembly of focusing lenses. 
         [0017]    In the exemplary embodiment of the present invention, each lens plate assembly is removably attachable to the case of the LED cinema light. In alternative embodiments, each lens plates may be removably attached directly to an LED module. In the exemplary embodiment, magnets are used as the means of attachment. The removably attachable lens plate assemblies allow for a variety of lighting effects to be achieved with the same LED cinema light by swapping out the lens plate assemblies for other lens plate assemblies having different optical properties. This feature of the LED cinema light of the present invention is particularly desirable in the movie, television and video production industries where it is often desirable to produce light with a variety of different characteristics. 
         [0018]    The above and other features of the invention will become more apparent from the following detailed description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]      FIG. 1  is a schematic front perspective view of an exemplary embodiment of the LED cinema light of the present invention. 
           [0020]      FIG. 2  is a schematic sectional view, taken along the line  2 - 2  of  FIG. 1 , with the lens plate assemblies removed, showing the arrangement of the component parts of the LED modules of the LED cinema light of  FIG. 1 . 
           [0021]      FIG. 3  is an enlarged schematic detail view of the area of circle  3  of  FIG. 1 , showing the arrangement of the component parts of the LED modules of the LED cinema light of  FIG. 1 . 
           [0022]      FIG. 4  is a schematic front detail view of an LED module of the LED cinema light of  FIG. 1 . 
           [0023]      FIG. 5  is a schematic sectional view, taken along the line  2 - 2  of  FIG. 1 , showing the relationship between an LED module and a lens plate assembly of the LED cinema light of  FIG. 1 . 
           [0024]      FIG. 6  is a schematic side view a removable lens plate assembly of the LED cinema light of  FIG. 1 . 
           [0025]      FIG. 7  is a schematic front view of a removable lens plate assembly of the LED cinema light of  FIG. 1 . 
           [0026]      FIG. 8  is a schematic view showing the relationship between an LED and a protective lens and a focusing lens, in accordance with the LED cinema light of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0027]    The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. The invention may, however, may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout. 
         [0028]    The term “light emitting diode” or “LED” refers to a particular class of semiconductor devices that emit visible light when electric current passes through them. The term light emitting electro-chemical cell” or “LEC” refers to any of a class of light emitting optoelectronic devices comprising a polymer blend embedded between two electrodes, which emit light in response to an electrical current. The term “artificial light source” or “ALS” refers to any controllable artificial luminescent device, including LEDs and LECs, and any other type of electrically controllable artificial light source. 
         [0029]    The term “plurality” as used in the specification and claims herein is to be interpreted as being coextensive with and inclusive of the term “at least one.” 
         [0030]    With reference to  FIGS. 1 through 7 , an LED cinema light  10  in accordance with the present invention is shown. The LED cinema light  10  generally comprises a plurality of LED modules  18  and a plurality of interchangeable or removable lens plate assemblies  20 , which are mounted in a case  12 . Each LED module  18  includes a plurality of LEDs  24  and each tens plate assembly  20  includes a plurality of focusing lenses  44 , wherein each focusing lens  44  of a lens plate assembly  20  corresponds to one LED  24  of an LED module  18 . The light produced by each individual LED  24  is focused and shaped by one of the corresponding focusing lenses  44 , as well as by one of a plurality of corresponding protective lenses  30 . 
         [0031]    With reference to  FIG. 1 , the LED cinema light  10  will typically include a mounting bracket  14  which pivotally attaches to the case  12  and pivotally attaches to a vertical light support  16 . This mounting arrangement provides the LED cinema light  10  with an adjustable field of illumination about two axes of rotation, i.e. the LED cinema light  10  may be rotated about a transverse axis corresponding to the pivotal attachment of the bracket  14  to the frame or case  12  and may also be rotated about a longitudinal axis corresponding to that of the vertical light support  16 . The vertical light support  16 , typically a tripod style support, also allows for vertical height adjustment of the LED cinema light  10 . 
         [0032]    With reference to  FIGS. 1 through 7 , each LED module  18  includes a base plate  22 , a plurality of the LEDs  24 , a plurality of heat sinks  26 , and a plurality of the protective lenses  30 . The base plate  22  is generally an elongated, rectangular aluminum extrusion. The base plate  22  has a front side  34  and a back side  36 . Attached to the front side  34  of the base plate  22  are a plurality of the LEDs  24  arranged as a linear array. The LEDs  24  and associated wiring  28  are attached to the front side  34  of the base plate  22  by means of a layer of insulative epoxy  32 . 
         [0033]    Attached to the back side  36  of the base plate  22  are a plurality of the heat sinks  26 . (In alternative embodiments, the base plate  22  and heat sink  26  may be fabricated as a single component.) For each LED  24 , there is one corresponding heat sink  26  which is mounted on the backside  36  of the base plate  22 , directly behind its corresponding LED  24 . On the front side  34  of the base plate  22 , attached over each individual LED  24  is one of the protective lenses  30 . The protective lenses  30  are secured to the front side  34  of the base plate  22  by means of the layer of insulative epoxy  32 . 
         [0034]    With reference to  FIG. 1 , the LED modules  18  are mounted in the frame or case  12  such that there is a longitudinal air gap  62  between each adjacent LED module  18  and a similar longitudinal air gap  62  between the LED modules  18  positioned adjacent to vertical members of the frame or case  12 . The longitudinal air gaps  62  assist in dissipating the heat generated by the LEDs  24  by allowing air flow past the LED modules  16  through the air gaps  62 . The cooling effect contributed by the longitudinal air gaps  62  is believed to be most significant when the LED Cinema light  10  of the present invention is pointed either straight up or straight down. 
         [0035]    With reference to  FIGS. 5-8 , each of the interchangeable lens plate assemblies  20  of the present invention LED cinema lamp  10  comprises a lens holding plate  38  having a front side  40  and a back side  42  and a plurality of holes or openings  46  wherein one of focusing lenses  44  is mounted in each of the holes  46 . The focusing lenses  44  are generally conical, refractive lenses and have an aperture  48 , an exit  50 , and a taper angle  52  (see  FIG. 6 ). The taper angle  52  may vary within the range of about 5 degrees to about 90 degrees, depending upon the lighting effect desired. In commercial embodiments, a variety of lenses with taper angles between 5 degrees and 90 degrees, in 5 or 10 degree increments are expected to be provided. 
         [0036]    In the LED cinema lamp of the present invention  10 , for each LED  24  of each of the LED modules  18 , there is the corresponding focusing lens  44  mounted on one of the corresponding lens plate assemblies  20 . The case  12  is configured such that the LED modules  18  are secured within the case and above each of the LED modules  18  is mounted one of the plurality of lens plate assemblies  20 . The lens plate assemblies  20  are configured such that one of the apertures  48  of each of the focusing lenses  44  is positioned about and just above one of the protective lenses  30  which covers each LED  24 . A desirable feature of the LED Light  10  of the present invention is that the lens plate assemblies  20  are quickly and easily removable from the case  12 . The ability to quickly remove and replace the lens plate assemblies  20  with other lens plate assemblies having focusing lenses of different optical characteristics provides a cinematographer with the ability to tailor the quality of the light emitted by the LEDs  24  to the needs of any particular scene. In the exemplary embodiment, the lens plate assemblies  20  are removably attachable to the frame or case  12 . In alternative embodiments, the lens plate assemblies may be removably attached directly to the LED modules  18 . 
         [0037]    In the exemplary embodiment of the LED cinema lamp  10 , the lens plate assemblies  20  include magnets  54 , mounted at each corner of the backside  42  of the lens holding plate  38 . The magnets  54  of the lens plate  20  are configured to mate with ferromagnetic regions  56  located on the frame or case  12 . The ferromagnetic regions  56  may also be magnets. The use of magnets to attach the lens plate assemblies  20  to the case  12  of the LED lamp  10  of the present invention is just one way in which the lens plate assemblies  20  may be removably coupled to the case. A person of skill in the art will understand that other quick release fasteners and mechanisms could be substituted for the magnets  54  and ferromagnetic regions  56 . 
         [0038]    With reference to  FIG. 8 , the relationship between each LED  24  and corresponding protective lens  30  and focusing lens  44  is shown in more detail. As shown in  FIG. 8 , light rays  60  emitted from the LED are focused into a generally circular beam by the combined action of the protective lenses  30  and focusing lenses  44 . By changing the optical characteristics of the focusing lenses  44 , a variety of lighting conditions can be produced. 
         [0039]    Not shown, but included with each LED cinema light are LED driver electronics required to operate the LEDs. Suitable electronics are commercially available and are known to those of skill in the art. 
         [0040]    In the exemplary embodiment, the case  12  of the LED light  10  is made from aluminum extrusions. Other materials, including molded plastic materials and formed sheet metal, are also suitable. The size of the case  12  is determined by the length of the LED modules  18  and the width of the case is determined by the number of LED modules  18  to be used in the case. The length and width of the LED modules  18  and that of the case  12  will vary depending upon the desired output wattage and intended purpose of the light. 
         [0041]    The configuration of the LED cinema lamp  10  of the present invention is flexible and can readily be scaled up or down to meet the needs of any particular task. In the exemplary embodiment of the LED cinema lamp  10  shown in  FIG. 1 , the LED modules  18  and corresponding lens plate assemblies  20  are shown in a vertical arrangement comprising vertical columns of LED modules  18  and lens plate assemblies  20 . It will be appreciated that the LED modules  18  and lens plate assemblies  20  may also be arranged in horizontal rows. Other arrangements are also possible. 
         [0042]    In the exemplary embodiment, the base plates  22  of the LED modules  18  are made from extruded aluminum. Aluminum is lightweight and has good thermal conductivity which renders is a good material choice for the base plates  22  which must have good heat conduction properties. Other nonferrous, as well as ferrous, metallic materials are also suitable. In the exemplary embodiment, the lens holding plates  38  of the lens plate assemblies  20  are also made from aluminum. Other materials which can withstand the heat output of the LEDs, including most metallic materials are also suitable. Some heat resistant plastic materials may also be suitable. The protective lenses  30  and focusing lenses  44  may be made from clear or translucent materials including glass and many plastics. 
         [0043]    In the exemplary embodiment, of the LED cinema light  10 , the protective lenses  30  are plano-convex lenses. However, other lens types such as plano-concave lenses are also suitable. In some alternative embodiments, the protective lenses  30  may also be clear or translucent protective covers which lack focusing properties. Likewise, in the exemplary embodiment of the LED cinema light  10 , the focusing lenses  44  are conical, refractive lenses. However, other lens types are also suitable such as Fresnel lenses. The focusing lenses  44  may be of variety of optical configurations to produce a variety of lighting characteristics. 
         [0044]    Suitable LEDs  24  for use in the present invention are commercially available and are known to those of skill in the art. In alternative embodiments, LECs or other artificial light sources may be substituted for the LEDs  24 . 
         [0045]    The foregoing detailed description and appended drawings are intended as a description of the presently preferred embodiment of the invention and are not intended to represent the only forms in which the present invention may be constructed and/or utilized. Those skilled in the art will understand that modifications and alternative embodiments of the present invention which do not depart from the spirit and scope of the foregoing specification and drawings, and of the claims appended below are possible and practical. It is intended that the claims cover all such modifications and alternative embodiments.