Abstract:
Disclosed is an LED lighting system with improved airflow and heat dissipation qualities. In one embodiment, the system comprises a heatsink mounted to an LED chip, and a fan assembly blowing air into the heatsink. The fan assembly includes a plurality of fans, the wind tunnels of the plurality of fans providing greater airflow in the center of the heatsink than a conventional one-fan configuration. In a further aspect, the disclosed system comprises a light head assembly in which cool air enters the light head assembly via the bottom and rear, and hot air is drawn out of the top of the light head assembly. An airflow path is created by selectively placing fans, baffles, walls, and openings in the lighting assembly.

Description:
TECHNICAL FIELD 
       [0001]    This invention relates to the field of heat dissipation, and more particularly to the field of heat dissipation systems used to cool LED-based lighting systems. 
       DESCRIPTION OF THE RELATED ART 
       [0002]    Light-emitting diodes (LEDs) have become increasingly popular in lighting applications. Some reasons for this include the fact that LEDs are generally more cost-effective, space-efficient, ecologically friendly, durable, and longer lasting than traditional incandescent or fluorescent lights, while also generating less heat. Although LED&#39;s generally generate less heat than other light sources, they still require cooling. Additionally, as LED lighting technology has progressed to produce greater light output using LEDs, there is a growing need for more efficient heat dissipation and cooling of these LED-based lighting systems. 
         [0003]    Previous heat dissipation systems in LED lighting systems have utilized passive heatsinks. These heatsinks are generally made of heat-conducting material and generally include a flat front surface that is in contact with an LED chip, and a rear surface with a plurality of extensions. The physical contact between the heatsink and the LED chip draws heat away from the LED chip, and the plurality of extensions provide surface area for dissipating the heat into the surrounding air. Active heatsinks (i.e., power-consuming heatsinks) generally provide a fan to blow air through the plurality of extensions to increase the heat dissipating effects. However, active heatsinks generally include a single fan blowing into the heatsink. A single fan creates a wind tunnel that has a dead spot in the center, which is generally the hottest region of a heatsink. As such, the heat dissipating effects of these active heatsinks are not maximized. 
         [0004]    Additionally, in LED-based lighting systems, the LED chip and heatsink are generally enclosed in a confined space. As such, the air around the LED chip and heatsink quickly becomes very warm, which hinders cooling of the LED chip. 
       BRIEF SUMMARY OF THE DISCLOSURE 
       [0005]    According to various embodiments, the apparatus, systems, and methods described herein relate to heat dissipation and cooling of LED systems. 
         [0006]    This invention may be embodied in an LED light assembly comprising an LED chip having a front surface and a rear surface and one or more LEDs on the front surface; a heatsink having a front surface, a rear surface, and a plurality of heatsink extensions extending from the rear surface, wherein the front surface of the heatsink is in physical contact with the rear surface of the LED chip; and a fan assembly positioned proximate the plurality of heatsink extensions. The fan assembly may comprise a plurality of fans that create wind tunnels when operated such that the wind tunnels overlap near a central region of the heatsink. 
         [0007]    In one aspect of this embodiment, the LED chip may have a wattage of greater than 400 W. The LED chip may also be a tungsten frequency LED chip, or, alternatively, a daylight frequency LED chip. 
         [0008]    In another aspect of this embodiment, the LED light assembly may be configured for use with the DMX512 communication standard. 
         [0009]    In a third aspect of this embodiment, the plurality of fans may be low-noise fans. The plurality of fans may also be arranged in a planar pattern. In a further aspect, the plurality of fans may be four fans arranged in a square pattern. 
         [0010]    In a fourth aspect of this embodiment, the heatsink may be a flared pin design, a straight pin design, a flared fin design, or a straight fin design. 
         [0011]    The present invention may also be embodied in an LED-based lighting system comprising an LED subassembly and a light head subassembly for enclosing the LED subassembly. The LED subassembly may comprise the components and characteristics of the LED light assembly embodiment discussed above. The light head subassembly may comprise an outer enclosure, an inner baffle house within the outer enclosure, and a second fan assembly having one or more fans. The inner baffle may comprise an open region through which air may pass, and the second fan assembly may be positioned proximate the open region of the inner baffle. In this embodiment, an air path may be created by the LED subassembly and the light head subassembly such that air is drawn into the light head subassembly and directed towards the heatsink by the LED subassembly&#39;s fan assembly, and air is drawn through the open region and out of the light head subassembly by the light head subassembly&#39;s fan assembly. In one aspect of this embodiment, the open region of the inner baffle may have a perforated surface so as to minimize light leak through the open region. 
         [0012]    Other features and aspects of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the features in accordance with various implementations. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    The drawings are provided for purposes of illustration only and merely depict typical or example implementations. These drawings are provided to facilitate the reader&#39;s understanding and shall not be considered limiting of the breadth, scope, or applicability of the invention. For clarity and ease of illustration, these drawings are not necessarily to scale. 
           [0014]      FIGS. 1A and 1B  provide front and rear perspective views, respectively, of an LED subassembly, in accordance with an embodiment of the present invention. 
           [0015]      FIGS. 2A-D  provide front, rear, side, and top views, respectively, of the LED subassembly of  FIG. 1 . 
           [0016]      FIG. 3  provides a deconstructed assembly view of the LED subassembly of  FIG. 1 . 
           [0017]      FIGS. 4A-B  provide front and rear perspective views, respectively, of a light head assembly, in accordance with an aspect of an embodiment of the present invention. 
           [0018]      FIG. 5  provides a deconstructed assembly view of the light head assembly of  FIG. 4 . 
           [0019]      FIGS. 6A-B  provide front and rear perspective views, respectively, of the LED heat sink assembly of  FIG. 1  inserted into the light head assembly of  FIG. 4 , in accordance with an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    In the following description, numerous specific details are set forth to provide a thorough understanding of various embodiments of the present invention. It will be apparent however, to one skilled in the art, that these specific details need not be employed to practice various embodiments of the present invention. In other instances, well known components or methods have not been described in detail to avoid unnecessarily obscuring various embodiments of the present invention. 
         [0021]    The present invention provides a heat dissipation system for an LED-based lighting system.  FIGS. 1A and 1B  provide front and rear isometric views of an LED subassembly  10  that embodies certain aspects of the disclosed system.  FIGS. 2A-D  provide front, rear, side, and top views, respectively, of the LED subassembly  10 . 
         [0022]    The LED subassembly  10  includes an LED chip  12  and a heatsink  16 . The LED chip  12  is generally an electrical chip having a front surface and a rear surface and one or more LEDs  22  centered on the front surface of the chip to produce light output. The heatsink  16  has a flat planar portion having a front surface and a rear surface. The front surface of the heatsink  16  is in contact with the rear surface LED chip  12 . The heatsink  16  is generally composed of heat conductive material so that the physical contact between the front surface of the heatsink  16  and the rear surface of the LED chip  12  causes heat from the LED chip  12  to escape into the heatsink  16 . 
         [0023]    On the front surface of the LED chip  12 , a conical reflector  20  surrounds the one or more LEDs  22  so as to intensify and direct the LED light output in a particular direction. The LED chip  12  and the conical reflector  20  occupy a central region on the front surface of the heatsink  16 . The outer edges of the heatsink&#39;s front surface are then mounted to a relay mounting bracket  14 . The relay mounting bracket  14  allows the LED subassembly  10  to be positioned inside a light head assembly, which will be described in greater detail later in this invention. 
         [0024]    On the rear surface of the heat sink, opposite the LED chip, are a plurality of flared pins  24 . The pins  24  on the rear surface of the heatsink  16  are also made of heat conducting material and provide increased volume to draw heat away from the LED chip  12 , and increased surface area through which heat may dissipate into the surrounding air. The heatsink  16  displayed in  FIGS. 1 and 2  is a flared pin fin design, with individual pins flaring outwardly from the rear surface of the heatsink  16 . However, it should be understood that the principles disclosed herein may be applied to many different heat sink designs, including, but not limited to, straight pin fin (columnar pins extending perpendicularly from the heatsink surface), straight fin (planar fins extending perpendicularly from the heatsink surface) and flared fin (planar fins flaring outwardly from the surface of the heatsink) designs. 
         [0025]    Also on the rear side of the heatsink  16 , proximate the pins  24 , is a fan assembly  17 . The fan assembly  17  includes four fans  18  mounted to the LED subassembly  10  by a fan frame  26 . The heatsink  16  is generally made of a heat-conductive material that is able to draw heat away from the LED chip  12 . The fans  18  blow air through the pins  24  on the heatsink  16  to increase the rate of heat dissipation by the heatsink  16 . Although the figures shows a four-fan assembly, the design may use more than 4 fans (e.g., six or eight fans), or reduce the number of fans (e.g., 2 or 3) to provide the same or similar effects in improving the efficiency of cooling the heatsink. 
         [0026]    Previously, active heatsink designs used in LED lighting applications have included a heatsink attached to a single fan blowing air into the pins or fins of the heatsink. However, this single-fan design blows a donut-shaped tunnel of air into the heatsink, which results in an airflow “dead-spot” in the center of the heatsink. This is problematic due to the fact that when an LED chip is centered on a heatsink, the center of the heatsink absorbs the most heat produced by the LED chip, making the center of the heatsink the hottest part of the heatsink. The multiple fan design depicted in  FIGS. 1 and 2  creates four tunnels of air, with all four tunnels intersecting at the center of the heatsink  16 , creating optimal heat dissipation in the hottest region of the heatsink. 
         [0027]      FIG. 3  provides an exploded assembly view of the LED subassembly  10 . As described above, the LED chip  12  has one or more LEDs  22  on its front surface, and its rear surface is mounted to a front surface of the heatsink  16 . The conical reflector  20  is also mounted to the front surface of the heatsink  16 , around the LED chip  12 , to surround the one or more LEDs  22 . The LED chip  12  and the conical reflector  20  occupy a central region of the heatsink  16 &#39;s front surface. The outer edges of the heatsink  16 &#39;s front surface are then mounted to the relay mounting bracket  14 . Four fans  18  are positioned on the rear side of the heatsink  16 , proximate the plurality of pins  24 . The fans  18  are attached to the fan frame  26  via screws or other attachment means. The fan frame  26  includes four openings on the rear surface that correspond to the positions of the four fans  18 , which enable the fans to draw air into the fans towards the heatsink  16 . The fan frame  26  also includes two side walls  27 , which aid in directing air upwards, the significance of which will be discussed in greater detail later in this invention. Four mounting brackets  28 , two on top and two on bottom, are provided to secure the fan frame  26  to the relay mounting bracket  14 . 
         [0028]    The LED/heatsink subassembly design depicted in  FIGS. 1-3  can be applied to any LED lighting system. However, it finds particularly useful application when used in film production. In film applications, LEDs of higher light outputs (i.e., higher lumens) may be desirable so as to provide sufficient lighting on a film set. In these high performance embodiments, the LED chip  12  may have a wattage of greater than 400-1000 W, producing light outputs that are equivalent to 2000 W to 6000 W of incandescent fixture. Future LED light fixtures are expected to use larger power supplies and larger LED chips, resulting in higher wattage output. The wattage in creating LED lights is not limited to these wattage values, and the present invention may be used to more efficiently cool LED lights of greater or lesser wattages. 
         [0029]    In particular embodiments, the LED chip  12  may be available in both tungsten and daylight industry standard frequencies. LED chips producing such high light outputs generally require more efficient cooling due to the fact that these high output chips can get very hot. As such, the disclosed heat dissipation system and its increased heat dissipation efficiency works to great advantage in cooling these high performance LEDs. In particular embodiments, it may be desirable for the lighting systems disclosed herein to be compatible with the DMX512 communications standard, which is a commonly used standard for electronically controlling lighting systems in films. 
         [0030]    Minimizing sound output is an important consideration when high performance lighting systems are used to aid in audio/visual recording. Typically, fans used to cool a lighting system are primarily responsible for any ambient noise created by the lighting system. A single fan with an inefficient wind tunnel path having a dead-zone in the center of the heatsink would require higher speeds to achieve the desired heat dissipation results. By implementing a four-fan design that more efficiently and effectively cools the lighting system, each of the fans in the presently disclosed system can be run at slower speeds. The slower fan speed reduces the noise created by the heat dissipation system, and, therefore, the overall noise output from the lighting system. In order to decrease the sound output of the lighting system, low noise fans may be used, such as a SilenX 80 MM fan. 
         [0031]    In another aspect of the present invention, a light head assembly is provided for use with the LED subassembly  10  described in  FIGS. 1-3 .  FIGS. 4A and 4B  provide front and rear isometric views, respectively, of a light head assembly  50  that may be used to house the LED subassembly  10 , in accordance with an aspect of the present invention. The light head assembly  50  is generally hollow and cylindrical in shape, and includes an outer enclosure  52  made up of two upper side panels  54  and two lower side panels  56 . On opposing ends of the cylindrical light head assembly  50  are a front ring  58  and a rear ring  60 , which assist in holding the outer enclosure components in place. 
         [0032]    On the front ring  58  are several locking clips  62  to hold lighting accessories, such as fresnel lenses, protective screens, color gel screens, or the like. On the sides of the light head assembly  50  are two trunnion plates  63 , which allow the light head assembly  50  to be rotatably attached to a swivel mount. On the rear end of the light head assembly  50  is an inner rear baffle  64  within an outer rear dome  66 . On the top surface of the light head assembly  50  is an inline fan assembly  68 . Each of these components and their functions will be discussed in greater detail with reference to  FIG. 5 , which provides an exploded assembly view of the light head assembly  50  to provide a clearer view of its inner-workings. 
         [0033]    As can more clearly be seen in  FIG. 5 , within the outer enclosure of the light head assembly  50  is an inner baffle  70 . The inner baffle  70 , much like the outer enclosure, is generally cylindrical in shape, but has an opening  72  on its bottom surface. The bottom opening  72  allows for the light head subassembly  10  of  FIGS. 1-3  to be inserted into the light head assembly  50 . The sides of the cylindrical inner baffle  70  are solid, i.e., closed, but the top surface of the inner baffle  70  has a perforated surface  74  with a plurality of perforated openings. The perforated surface  74  may simply be an opening or any other open configuration. However, a perforated surface may be preferable in certain applications, as the perforated pattern provides some protection with regard to light leaking out of the top of the light head assembly  50 . 
         [0034]    The perforated surface  74  lies directly beneath the in-line fan assembly  68  of the outer enclosure. These two components work together to form an airflow path within the lighting assembly to maximize heat dissipation within the assembly. The rear of the light head assembly  50 , as discussed above, includes an inner rear baffle  64  within a rear dome  66 . Both of these components include openings for air to pass through. These openings on the rear of the light head assembly  50  are positioned proximate the fan assembly  17  of the LED subassembly  10 . 
         [0035]    The fan assembly  17  draws cool, outside air into the light head assembly  50  through the openings in the rear baffle  64  and the rear dome  66 . The four-fan configuration of the fan assembly  17  directs this cool airflow to the heatsink  16 , with the airflow being focused on the hottest area of the heatsink, its center. The cool air carries heat away from the heatsink  16 , allowing the heatsink to draw additional heat away from the LED chip  12 . The release of heat into the air results in warming of the air surrounding the heatsink area. The perforated surface  74  on the top of the inner baffle  70  provides a route through which this hot air may escape the light head assembly  50 . The in-line fan assembly  68 , positioned on the top of the light head assembly  50 , is positioned to draw hot air from inside the light head assembly  50  out through the perforated surface  74 . Hot air is further directed upwards towards the perforated surface  74  and the in-line fan assembly  66  by the side walls  27  of the fan frame  26  (shown in  FIGS. 1-3 ). 
         [0036]    In summary, the fans  18  in the LED subassembly  10 , the in-line fan assembly  68 , the side walls  27  of the fan frame  26 , and the strategic placement of openings in the inner baffle  70  create an airflow path to maximize heat dissipation: (1) cool air is drawn in through the rear of the light head  50  (i.e., inner rear baffle  64  and rear dome  60 ) by the fans  18  on the LED subassembly  10 ; (2) the cool air is directed by the fans  18  to the heatsink  16  such that the wind tunnels are focused on the center of the heatsink  16  to carry heat away from the heatsink, resulting in the cool air being warmed; and (3) the now-hot air is drawn out of the light head assembly  50  through the top perforated surface  74  by the in-line fan assembly  68 . The flow of air through this path allows for cool air to continually enter the light head assembly  50 , while hot air is continually blown out of the light head assembly. 
         [0037]      FIGS. 6A and 6B  depict the LED subassembly  10  positioned within the light head assembly  50 . The LED subassembly  10  is mounted to a trough  80 , which is mounted to the light head assembly  50 . Controls on the trough  80  allow a user to control operation of the light head assembly  50  (e.g., turning the light on or off, dimming the light, focusing or de-focusing the light beam, etc.). The light head assembly  50  is rotatably mounted on a swivel mount  90 , which allows for the direction of the light beam to be adjusted by rotating the light head assembly  50 . In  FIG. 6A , exterior surfaces on the front of the lighting assembly have been removed to provide a clear view of the LED subassembly  10  mounted in the trough  80  and positioned within the light head assembly  50 . In  FIG. 6B , the rear portions of the light head assembly  50  (e.g., the inner rear baffle  64  and rear dome  66 ) have been removed to more clearly show the placement of the LED subassembly  10  within the light head assembly  50 . 
         [0038]    In the foregoing specification, embodiments of the invention have been described with reference to specific exemplary features thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention. The specification and figures are, accordingly, to be regarded in an illustrative rather than a restrictive sense. Although the invention has been presented with reference only to the presently preferred embodiments, those of ordinary skill in the art will appreciate that various modifications can be made without departing from this invention. Accordingly, this invention is defined only by the following claims.