Abstract:
An improved LED soft light is disclosed, which comprises a trough assembly; a plurality of LED light assemblies housed within the trough assembly, each of the LED light assemblies comprising one or more LEDs to emit light and an Primary reflector surrounding the one or more LEDs to direct the light emitted by the one or more LEDs; and a secondary reflector positioned proximate a rear portion of the trough assembly to reflect the light emitted by the plurality of LED light assemblies and direct the emitted light out of the front of the soft light.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates generally to lighting devices, and more particularly to LED soft lights. Soft lights are generally used to create diffuse light that casts “soft” shadows or eliminates shadows entirely. Soft light results when light is bounced or diffused over a relatively large surface. Soft lights will generally utilize a combination of light sources to effectively create a single, large light source that casts diffuse light over a subject, creating softer shadow lines. However, it is often difficult to combine light sources into a single diffuse light source without creating “hotspots” that are generated by each of the individual light sources. 
         [0002]    Soft lights generally utilize two primary means for creating soft light: shining light through a large frame of diffusion (often called “direct diffusion” lights); or bouncing light off a large white surface (often called “bounce lights”). Direction diffusion lights typically offer the conveniences of portability and lower costs, while bounce lights tend to offer a higher quality of light. As such, large studios or high-end productions tend to prefer bounce-type soft lights for the higher quality light produced by these lights. 
         [0003]    Light emitting diodes (LEDs) are becoming more popular in lighting applications due to the fact that they are able to produce high intensity light with reduced power usage and heat output. However, creating a soft light using LEDs presents unique challenges. LEDs emit directed, high intensity light from a small surface area, leading to greater challenges in creating sufficient soft light output while also avoiding hotspots. While greater diffusion of the light will lead to softer light output with fewer hotspots, it also lowers the overall light output intensity. 
         [0004]    It can readily be appreciated that there is a need for an LED soft light that emits soft light from a plurality of LED light sources with sufficient light output while remaining sufficiently soft. The present invention fulfills these needs and provides further related advantages. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention resides in an LED soft light in which a plurality of LED light assemblies having primary reflectors direct light towards a curved white secondary reflector. The light is reflected off of the curved, white secondary reflector and directed out of the soft light. 
         [0006]    In a presently preferred embodiment of the invention, the soft light comprises a trough assembly; a plurality of LED light assemblies housed within the trough assembly, each of the LED light assemblies comprising an LED chip having one or more LEDs to emit light and a primary reflector surrounding the one or more LEDs to direct the light emitted by the one or more LEDs, each primary reflector having a reflector angle and a reflector height; and a secondary reflector having a radius of curvature and a curved, white reflection surface, the secondary reflector positioned proximate a rear portion of the trough assembly to reflect the light emitted by the plurality of LED light assemblies, wherein each primary reflector directs the light emitted by the one or more LEDs surrounded by the primary reflector towards the secondary reflector, and the light directed towards the secondary reflector by each of the primary reflectors is reflected by the white reflection surface of the secondary reflector and directed out of a front region of the soft light. 
         [0007]    In the presently preferred embodiment, the reflector angle of each primary reflector may be between approximately 45 and 65 degrees, inclusive, and the reflector height may be between approximately 1 inch and 3 inches, inclusive. In a more particular aspect of this embodiment, the reflector angle may be approximately 55 degrees, and the reflector height may be approximately 2 inches. The reflector may comprise mirror-finish aluminum sheet material. 
         [0008]    The secondary reflector of the presently preferred embodiment may have a radius of curvature between approximately 12 inches and 18 inches, inclusive. In a related aspect of this embodiment, the soft light may further comprise a curvature adjustment mechanism to adjust the radius of curvature of the secondary reflector. In a further aspect, the curvature adjustment mechanism may adjust the radius of curvature between approximately 12.25 inches and approximately 17.25 inches, inclusive. The secondary reflector may comprise low gloss white aluminum. 
         [0009]    Each LED chip may be a 150 Watt (“W”) LED chip. The distance from each LED chip to the secondary reflector, measured perpendicular to the LED chip, may be between approximately 4 and 6 inches, inclusive. In a further aspect, the distance from each LED chip to the secondary reflector may be between approximately 4.95 and 5.00 inches, inclusive. 
         [0010]    Each of the plurality of LED light assemblies may be positioned such that the light emitted by the plurality of LED light assemblies is directed towards the secondary reflector at a predetermined angle, the predetermined angle being defined relative to the normal of the tangent line to the secondary reflector at the point of intersection of the emitted light and the secondary reflector. The predetermined angle may be calculated so as to direct the emitted light off the secondary reflector and out of a front region of the soft light. The predetermined angle may be between 30 and 45 degrees, or, more particularly, approximately 37 degrees. 
         [0011]    These and other features and advantages of the invention should become more readily apparent from the detailed description of the preferred embodiments set forth below taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    Embodiments of the present disclosure will now be described, by way of example only, with reference to the following drawings. 
           [0013]      FIG. 1  provides a perspective view of an LED soft light having four LED assemblies, in accordance with an embodiment of the present invention. 
           [0014]      FIG. 2  provides a perspective view of an LED soft light having two LED assemblies, in accordance with another embodiment of the present invention. 
           [0015]      FIG. 3A  provides a front plan view of the four LED assemblies of the soft light of  FIG. 1 . 
           [0016]      FIG. 3B  provides a perspective view of the four LED assemblies of the soft light of  FIG. 1 . 
           [0017]      FIG. 4  provides an internal perspective view of the LED soft light of  FIG. 1 . 
           [0018]      FIG. 5  provides an internal right plan view of the LED soft light of  FIG. 1 . 
           [0019]      FIG. 6  provides a rear perspective view of the LED soft light of  FIG. 1 . 
       
    
    
     DESCRIPTION OF THE INVENTION 
       [0020]    Referring now to the drawings, the present invention resides in a LED soft light which emits diffuse, soft light by reflecting the light output from a plurality of LED light sources off of a large, white reflector.  FIG. 1  provides a perspective view of an LED soft light  10 , in accordance with an exemplary embodiment of the present invention. The LED soft light  10  includes a trough assembly  12 , a secondary reflector  14  having a white reflection surface, and four LED assemblies  16  housed within the trough assembly and directed towards the secondary reflector  14 . On either side of the four LED assemblies  16  are side panels  11 , which may be made of the same material as the secondary reflector  14  or some other reflective material to assist in reflecting the light emitted by the LED assemblies  16 . The front region of the trough assembly  12  has an opening  15  through which the bounced light exits the soft light  10 . While the opening  15  is shown in the figures as an open space, it should be understood that the opening  15  may include transparent or semi-transparent material through which the bounced light may exit. The opening  15  is surrounded by guide rails  21  that may receive filters such as a diffusion filter, color filter, or egg crate that is positioned over the opening  15  to create different effects on the output light. 
         [0021]    A safety screen  18  surrounds the four LED assemblies  16  to restrict access to the electronics within the trough assembly  12 . The safety screen  18  is also perforated so as to allow ventilation of heated air inside the trough assembly  12  that is generated by the LED assemblies and other electronics. The trough assembly  12  is rotatably connected to a yoke  20 . The yoke  20  includes a  5 / 8  receiver  22  to mount the yoke on a lighting stand or otherwise secure the LED soft light  10  to a mount so that it can be positioned to provide light in a particular direction. The yoke  20  is rotatable about the trough assembly  12 , but may be secured in a particular position to lock the LED soft light  10  in a desired position. In the embodiment shown, the yoke  20  may be locked in place by rotating and tightening a clamp knob  24 . The clamp knob  24  may be loosened to allow the yoke  20  to rotate about the trough assembly  12 . 
         [0022]    It should be understood that while the present disclosure will discuss the LED soft light  10  embodiment shown in  FIG. 1  having four LED assemblies  16 , the disclosed invention is not limited to this number of LED assemblies and may be applied to any sized LED soft light having any number of LED assemblies. For example,  FIG. 2  provides another embodiment of an LED soft light  25  which has two LED assemblies  16 . 
         [0023]      FIGS. 3A and 3B  provide close-up views of the four LED assemblies  16 . Each LED assembly comprises an LED chip  30  that includes one or more LEDs for emitting light and a primary reflector  32 . The LED chip  30  may be any appropriate LED chip. In a preferred embodiment, the LED chip  30  is a 26 mm, 150 W LED chip, such as the 150 Watt Mole-Richard Quantum Dot LED. The primary reflector  32  surrounds the one or more LEDs of each LED chip  30  and at least partially directs the light emitted by the LED chip  30  towards the secondary reflector  14 . By partially directing the light emitted by each LED chip  30 , the primary reflectors  32  increase the amount of light directed towards and reflected by the secondary reflector  14  (discussed in greater detail below), thereby increasing the amount of light output by the soft light  10 . 
         [0024]    The primary reflector  32  can affect the light output of the soft light  10  and may be varied depending on the desired light output characteristics. For example, the shape of the primary reflector  32  will affect its effectiveness in reflecting the light from each LED chip. In the preferred embodiment shown in  FIGS. 3A and 3B , each primary reflector  32  is frusto-conical in shape and has a conical angle. The conical angle of the primary reflector  32  is labeled as angle  40 . A frusto-conical shape has been found to approximate or meet the performance of a parabolic reflector, while being generally easier and more cost-effective to manufacture. Alternatively, the primary reflectors may be parabolic, of course, or another appropriate shape. 
         [0025]    Altering the angle  40  created by the primary reflector  32  will generally alter the intensity and directedness of the light emitted by the LED chip  30 . Narrowing the angle  40  will generally result in a more directed, narrower beam of light being directed towards the secondary reflector  14 , while widening the angle  40  will typically result in a wider beam with less direction. Altering the height  42  of the primary reflector  32  will also affect light output characteristics by varying how much light is captured and directed by the primary reflector  32 . Using a primary reflector  32  with a shorter height will generally result in less light being reflected and directed by the primary reflector  32 , as compared to a taller primary reflector. The exact angle and height of the primary reflector will depend on the size and light output characteristics of the LED chip  30 , the size of the soft light  10 , and the desired overall light output characteristics. In a presently preferred embodiment, using 26 mm, 150 W LED chips  30 , such as the 150 Watt Mole-Richardson Quantum Dot LED, the reflector angle  40  may range from approximately 45 to 65 degrees, with a further preferred measure of approximately 55 degrees, and the height of the primary reflector  32  may range from approximately 1 to 3 inches, or more preferably from approximately 1.5 to 2.5 inches, with a further preferred height of approximately 2 inches. 
         [0026]    The material of the primary reflector may also be varied to affect the light output characteristics of the soft light  10 . In order to maximize light output, it may be preferable to use a highly reflective material. An example of a highly reflective material that may be used to form the primary reflector  32  is 0.020-inch thick mirror finish aluminum sheet material. However, other lighting effects may be desired which require less light output, and other materials may be used depending on the desired effect. 
         [0027]    Each LED assembly  16  shown in  FIGS. 3A and 3B  further comprises a heatsink  34  and a fan  36  to remove heat from the LED chip  30 . While the figures show a fin-type heatsink with a fan  34  to move heated air away from the heatsink  36 , it should be understood that any appropriate cooling mechanism and/or heatsink may be used. 
         [0028]      FIGS. 4 and 5  provide more detailed internal views of the soft light  10  to depict how light is directed from the LED assemblies  16  to the secondary reflector  14  and reflected out of the soft light  10 . In  FIG. 4 , it can be seen that each of the LED assemblies  16  is mounted within the trough assembly  12  and directed at an upward angle towards the secondary reflector  14 . 
         [0029]      FIG. 5  provides a right plan view of the soft light  10 . The LED assembly  16  is directed upwards towards the secondary reflector  14 . The secondary reflector  14  has a white reflection surface off of which the light from the LED assemblies  16  is reflected. The secondary reflector  14  may also have a pre-determined radius of curvature. A beam of light  60  is emitted from the LED assembly  30  towards the secondary reflector  14 , reflected off the white reflection surface of the secondary reflector, and then exits the soft light  10 . Reflection of the light off of the white reflection surface of the secondary reflector results in diffuse, soft light. 
         [0030]    The radius of curvature of the secondary reflector  14  and the distance of the LED chip  30  from the secondary reflector  14  (marked as distance  54  in  FIG. 5 ) will affect the properties of the light emitted by the soft light  10 . Increasing the distance  54  will result in greater light spread before it reaches the secondary reflector  14 , yielding more diffuse light of lower intensity. In a preferred embodiment, using a 26 mm, 150 W LED chip and the preferred primary reflector dimensions discussed above, the distance  54  from the LED chip  30  to the secondary reflector is between approximately 4.75 and 5.25 inches, and in a further preferred embodiment, is between approximately 4.95 and 5.00 inches. Changing the radius of curvature will also affect the softness and intensity of the light. In a preferred embodiment, in order to maximize light output, the radius of curvature is between approximately 12 and 18 inches, and, more preferably, is approximately 15 inches. The secondary reflector may have constant radius of curvature throughout, or it may have a varying radius, in which case, the radius of curvature may be measured or approximated at the point of intersection of the beam of light  60  and the secondary reflector  14 . This preferred embodiment results in a soft light with a very high light output, wherein the light emitted from the four LED assemblies  30  is sufficiently blending to cast a diffuse, soft light. In a preferred embodiment, the desired light output is approximately 12,500 lumens for each LED assembly. Therefore, for the four-light configuration shown in  FIG. 1 , the desired light output is at least approximately 50,000 lumens, and for the two-light configuration shown in  FIG. 1 , the desired light output is at least approximately 25,000 lumens. 
         [0031]    Similar to the primary reflectors  32 , the material of the secondary reflector  14  may impact the intensity and softness of light reflected. For example, there are numerous shades of white that may be used to offer different softness or light level characteristics. Further, the texture of the white reflection surface of the secondary reflector  14  will affect the softness of the bounced light, and the reflectance of the white reflection surface will affect both softness and the amount of light reflected, i.e., light output level. The exact material selected will depend on the level of softness and light output desired for a particular application. In some applications, it may be desirable to use a material that will sufficiently diffuse the light to combine and soften the light output while still being highly reflective so as to maximize the diffused light output. An example of such a material is 24 gauge low gloss white aluminum, which has a reflective white surface that diffuses the emitted light while maintaining high light output. 
         [0032]    It can be seen in the figures that the beam of light  60  reflected off of the secondary reflector  14  exits through an opening  15  in the front region of the soft light  10 . As discussed above, the opening  15  may be an opening, or a transparent or semi-transparent material through which the light exits the soft light. In order to maximize the light output by the soft light  10  and minimize interference by the upper and lower bounds of the exit opening  15 , it may generally be desirable for the beam of light  60  to be directed towards the center of the exit opening  15 . In order to effectively direct the beam of light  60  towards the center of the exit opening  15 , the LED assembly  16  is mounted to a rear panel  50  of the trough assembly  12  at a pre-determined angle. The angle from the rear panel  50  to the LED chip  30  is marked as angle  52 . This angle  52  determines the angle at which the light emitted from the LED assembly  30  is directed towards the secondary reflector  14 . The secondary reflector&#39;s radius of curvature and the angle  52  of the LED assembly  16  generally determine the direction of the beam of light  60  reflected off of the secondary reflector  14  and emitted by the soft light  10 . In the preferred embodiment described above, the angle  52  of the LED chip to the rear panel  50  may be between approximately 60 and 80 degrees, with a preferred measurement of approximately 72 degrees. This embodiment results in the beam of light  60  reflecting off the secondary reflector  14  at an angle between approximately 25 and 45 degrees from the normal line at the point of reflection, or, more preferably, between approximately 35 and 40 degrees. The tangent and normal lines are depicted in  FIG. 5 , and the angle of light beam  60  is marked as angle  65 . In the depicted embodiment, the LED assembly  30  is angled from the rear panel  50  (angle  52 ) at approximately 72 degrees, which results in the light beam  60  intersecting the secondary reflector  14  at an angle of approximately 37 degrees relative to the normal line at the point of intersection (angle  65 ). This particular angle of reflection results in the beam of light  60  exiting the soft light  10  at close to the center of the exit opening  15  so as to maximize light output. 
         [0033]    By changing the secondary reflector  14 &#39;s radius of curvature, the softness and intensity of the light may be slightly varied. In  FIG. 5 , it can be seen that the secondary reflector  14  has a vertical edge  56  at its top end which is in contact with a set of screws  44 . In the embodiment shown in  FIGS. 4 and 5 , the radius of curvature of the secondary reflector  14  may be adjusted by moving screws  44  in or out. As the screws  44  are moved inward, the vertical edge  56  is pushed inward, decreasing the radius of curvature of the secondary reflector  14 . As the screws  44  are moved outward, the vertical edge  56  also moves outward, and the radius of curvature is increased. In a preferred embodiment, the screw is approximately 0.5 inches in length, and adjusting the position of the screw may result in the radius of curvature being adjusted from a range of approximately 12.25 inches to 17.25 inches. 
         [0034]      FIG. 6  provides a rear perspective view of the soft light  10 . The rear panel  50  of the trough assembly  12  includes several connections and controls with which to control the soft light  10 . In the depicted embodiment, the rear panel  50  includes two DMX control connections  70  which allow a DMX controller to be connected to the soft light  10  for remote control of the light. A counter  72  allows the user to set a control channel for the soft light  10  such that individual soft lights or groups of soft lights may be controlled by one or more DMX controllers based on the channel setting of each soft light. For example, if one soft light is set to channel 1, and three soft lights are set to channel 2, then the one channel 1 soft light can be controlled individually by a DMX controller set to control channel 1, and the three soft lights set to channel 2 may be controller by the same or a different DMX controller set to control channel 2 devices. A DMX status LED  74  indicates whether DMX control is activated. 
         [0035]    A switch  76  switches the soft light  10  between manual mode, in which the soft light  10  is controlled manually, and DMX mode, in which the soft light is controlled via DMX controller. A control knob  78  allows for manual dimming of the soft light  10  when the switch  76  is set to manual control. A power switch  80  controls power to the soft light  10 . 
         [0036]    Although the invention has been disclosed with reference only to presently preferred embodiments, those of ordinary skill in the art will appreciate that various modifications can be made without departing from the invention. The specification and figures are, accordingly, to be regarded in an illustrative rather than a restrictive sense. As such, the present invention is defined only by the following claims and recited limitations.