Abstract:
The present disclosure provides a lighting device that includes an array of LEDs arranged on a circuit board with a reflector that rotates relative to the LEDs to reflect the light in various directions. The reflector according to the present disclosure includes a compact construction that allows for effective light reflection. A related lighting system and method is also provided.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 12/341,666 filed Dec. 22, 2008, the disclosure of which is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure provides a rotating lighting device wherein the light source includes light emitting diodes. 
     BACKGROUND 
     Rotating light sources are commonly used as warning lights. In some common applications the rotating lights are mounted to emergency response vehicles such as police vehicles and ambulances. In other common applications rotating lights are used mounted to the outside of aircraft or mounted to stationary objects such as radio towers. 
     Some rotating lights are configured such that the light source itself rotates, while others are configured so that the light source is stationary and mirror(s) are rotated to reflect the light in various directions. Traditionally, incandescent light sources are used in rotating lighting devices. 
     However, since light emitting diodes (LEDs) are long-lasting and efficient, attempts have been made to develop LED-based rotating lights. See, for example, US Pat. Publ. No. 2006/0209542 titled LED Based Rotating Beacon; US Pat. Publ. No. 2007/0263376 titled Rotating LED Beacon; and U.S. Pat. No. 6,461,008 titled LED Light Bar. Improved LED-based rotating lights are needed. 
     SUMMARY 
     The present disclosure provides a lighting device that includes an array of LEDs arranged on a circuit board with a reflector that rotates relative to the LEDs to reflect the light in various directions. The reflector according to the present disclosure includes a compact construction that allows for effective light reflection. A related lighting system and method is also provided. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is a perspective view of a rotating light according to an embodiment of the present disclosure; 
         FIG. 2  is an exploded assembly view of the rotating light of  FIG. 1 ; 
         FIG. 3  is a top view of the rotating light of  FIG. 1 ; 
         FIG. 4  is a cross-sectional view of the rotating light along line  4 - 4  of  FIG. 3 ; 
         FIG. 5  is a cross-sectional view of an alternative embodiment of the rotating light of  FIG. 4 ; 
         FIGS. 6   a - b  are perspective views of reflective areas of the rotating light of  FIG. 1 ; 
         FIG. 7  illustrates the light concentration feature of the rotating light of  FIG. 1 ; 
         FIG. 8  is a view illustrating the low profile feature of the rotating light of  FIG. 1 ; 
         FIG. 9  is a graph illustrating the effect of the faceted reflecting areas of the rotating light of  FIG. 1 ; and 
         FIG. 10  is an illustration of the LED array function correlated to the position of the reflector. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , a rotating light  10  according to an embodiment of the present disclosure is shown. The rotating light  10  includes a circuit board  12  that supports an array of LEDs  14  and a reflector  16  that is configured to rotate relative to the LEDs  14 . 
     Referring to  FIG. 2 , the components of the rotating light  10  are described in further detail. The circuit board  12  can be any type of circuit board that is capable of delivering power to the LEDs  14  that are connected thereto. In some embodiments the circuit board  12  includes a base that is made of metal or other material with sufficient heat transmission properties. 
     In the depicted embodiment a number of LEDs are spaced apart and arranged in a circle on the circuit board  12 . Optical elements  18  are positioned between the LEDs  14  and the reflector  16 . The optical elements  18  can be used to collimate the light emitted by the LEDs. In the depicted embodiment the optical elements  18  include a reflector cup ring  20  and a Fresnel lens ring  22 . It should be appreciated in alternative embodiments that include optical elements  18 , the optical elements  18  could take many different forms. For example, they could be parabolic reflectors, TIR lenses, or conventional lenses, or other optical elements. 
     In the depicted embodiment an electric motor  24  is shown mounted to the reflector cup ring  20  and extending through an aperture in the Fresnel lens ring  22 . The electric motor includes a drive shaft  26  that drives the rotation of the reflector  16 . In the depicted embodiment the drive shaft  26  defines the axis of rotation of the reflector  16 , which is concentric about the circular array of LEDs  14 . The depicted configuration in which the motor  24  is nestled between the reflector and the LEDs allows for a compact assembly. In some embodiments the motor  24  is wired to a remote power source, in other embodiments the motor is powered by a local rechargeable power source. It should be appreciated that the rotation of the reflector  16  could also be driven by a motor positioned at a different location (more remote from the reflector) via gears, belts, magnetic coupling, etc. Such a configuration may be used in a light bar type application where multiple reflectors and LED arrays are arranged in a single lighting unit. 
     Referring to  FIGS. 2-4 , the reflector  16  is configured to rotate over the array of LEDs and cause the light emitted from the LEDs to rotate. In the depicted embodiment, as the reflector  16  rotates, different LEDs are aligned with the first and second reflective areas. In other words, at any point in time at least one LED is aligned with the first reflective area, but not aligned with the other reflective area. 
     In the depicted embodiment the reflector  16  includes a first member  28  with a first reflective area  32 , and a second member  30  with a second reflective area  38 . In the depicted embodiment the reflector  16  also includes apertures  42 ,  44  that allow light to emit through the reflector in the vertical direction (see  FIG. 3 ). This feature enables the light to be easily located from a vantage point above the light (for example by a helicopter following a chase wherein the light is mounted to the roof of a police vehicle). 
     In the depicted embodiment the first reflective area  32  is positioned to receive light from a first group of LEDs, and the second reflective area  38  is positioned to receive light from a second group of LEDs. In the depicted embodiment the second reflective area  38  directly reflects the light in the same direction as the light reflected from the first reflective area  32 . As discussed above, the array of LEDs is arranged in a circle. It should be appreciated that may other LED arrangements are also possible (e.g., multiple rings of LEDs arranged in a circle, LEDs arranged in rectangular arrays, etc.). 
     Referring to  FIG. 5 , an alternative embodiment is shown wherein In the depicted embodiment the reflector  16  includes a third reflective area  36  that is positioned to receive light reflected from the second reflective area  34  and reflect the light in generally the same direction as the light being reflected by the first reflective area  40 . 
     In each of the above two depicted embodiments the light reflected from the first reflective area  32 ,  40  is reflected in a first direction “A” forming a first row “C” of reflected illumination, and the light reflected from the other reflective area (second and third reflective areas  34 ,  36  as in the embodiment shown in  FIG. 5 , or second reflective area  38  as in the embodiment shown in  FIG. 6 ) is reflected in generally the same direction (“A”) forming a second row “B” of reflected illumination that is adjacent the first row “C”. In some embodiment the rows are spaced apart (see  FIG. 5 ) and in other embodiment the rows are stacked one on top of the other (see  FIG. 4 ). It should be appreciated that many other configurations are also possible. 
     Referring to  FIGS. 6   a - b , the reflective areas of the reflector are shown in greater detail. In the depicted embodiments the at least one of the reflective areas has a curved edge profile. In the depicted embodiment the upper and/or lower edge profiles of reflective areas are correlated with the inner and outer diameter of the circular array of LEDs, respectively (i.e., the curve of the edge profile matches the curved arrangement of the LEDs). Moreover, in the depicted embodiments the first reflective area  32 ,  40  is convex and the other reflective area  34 ,  36 ,  38  is concave. In the depicted embodiments the first reflective area  32 ,  40  includes 10-20 facets, each oriented at about 45 degrees relative to the horizontal direction. The other reflective area  34 ,  36 ,  38  includes 10-20 facets which are also oriented at about 45 degrees relative to the horizontal direction. 
     Referring to  FIGS. 7-8 , a view directly into the reflected illumination is shown. The arrangement on the right depicts two adjacent rows of illumination “B”, “C”, which are the output from an embodiment of the reflector  16  of the present disclosure. The arrangement on the left illustrates the reflected illumination output from the standard reflector  48  (see  FIG. 8 ). The output from the standard reflector  48  includes a ring of illumination  46  that surrounds a dark center area. The reflector  16  of the present disclosure is configured to provide a concentrated reflected light output. It should be appreciated that in alternative embodiments, the light output from the reflector can be more or less concentrated than what is shown in  FIG. 7  (e.g., the reflected light output need not be in straight rows adjacent to each other). 
     Still referring to  FIGS. 7-8 , an embodiment of the light is shown fitted overlaid with a standard reflector  48  for comparison. In order to reflect light emitted from each of the LEDs in a horizontal direction, the standard reflector  48  must extend much higher than the reflector  16  of the present disclosure. For example, if the LEDs are arranged in a circular array with a diameter of D 1  (e.g., 4.8 inches), the height of the reflector  48  would be about H 2  (4.8 inches) to reflect the vertical light emitted from each LED in a generally horizontal direction. However, for the same configuration of LEDs the reflector  16  of the depicted embodiment would only be about H 1  (2.1 inches) high to reflect the light emitted from the LEDs in a generally horizontal direction. In the depicted embodiment of the reflector  16 , the height H 1  of the reflector  16  is between ⅓ to ⅔ of the diameter D 1  of the circular array of LEDs. 
     Referring to  FIG. 9 , a chart is shown that shows that the facets on the reflectors improve the uniformity of the illumination intensity as compared to unfaceted reflectors of otherwise the same configuration. The unfaceted mirror exhibits a peak-to-valley variation in the illumination intensity of 30 percent, while the variation exhibited by the facets of the depicted embodiment is about 7 percent. 
     Referring to  FIG. 10 , in the depicted embodiment at least one of the LEDs is not aligned with the reflective areas of the reflectors. The unaligned LED is selectively turned off momentarily to facilitate cooling. This cooling feature can be accomplished by employing a control unit that synchronizes the on and off function of the LEDs to the position of the reflector  16 . Since the LED is turned off when it is out of alignment with the reflective areas, the brightness of the reflected light is not adversely affected. The arrows in  FIG. 10  depict the direction of light propagation, which is correlated with the orientation of the reflector  16 , over a particular time period. In the depicted embodiment two LEDs positioned at the sides of the reflector  16  are turned off at any one time for cooling purposes. 
     It should be appreciated that in other embodiments of the present disclosure, the LED is turned off momentarily for cooling even if it is aligned with one of the reflective areas, the affect on the brightness of the reflected light may be acceptable given the large number of LEDs that are illuminated at any one time. It should also be appreciated that in alternative embodiments, other means for cooling the LED may be used. For example, the reflector can be configured so that the rotation causes air flow, which cools the LEDs. The depicted configuration does force some airflow around the LED for added cooling. Many different mechanisms for selectively turning on and off the LEDs are possible. 
     In the depicted embodiment the rotation of the reflector  16  can be controlled so that the rotational speed can be changed. In some embodiments, the rotational speed is changed based on the velocity of the vehicle. For example, if the vehicle is moving faster, the reflector  16  may be slowed when the reflected light beam is generally facing in the direction of travel to provide more light in that direction. The rotation is controlled so that it spans a smaller angle range than the full 360 degrees. For example, the rotation can be set to sweep back and fourth through 180 degrees. The rotation of the reflector  16  can also be stopped at a particular orientation so that the light can be used as a spot light to provide constant light in one direction. 
     It should be appreciated that in some embodiments the array of LEDs  14  can be single color LEDs of the same color, in other embodiments the LEDs can be single color LEDs of different colors, and in yet other embodiments the LEDs can be multi-color LEDs (an individual LED that is configured to emit light of more than one color). In embodiments that include an array of LEDs of different colors or multiple color LEDs, the rotating light can be configured so that the light emitted can be changed based on the specific application of the rotating light. It should be appreciated that in the embodiments that include LEDs of different colors, the light emitted can be of a color that is different than the colors of the LEDs since activating two different colored LEDs can result in light having a third color (e.g., a combination of LEDs that are red, green, and blue can results in the rotating light being able to reproduce most colors). In other words, the selective activation of lights can enable the light emitted from the rotating light to be the color of some of the LEDs as well as colors that result from the mix of colors of the LEDs. 
     It should also be appreciated that alternative embodiments can include more reflectors so that the light emitted from the LEDs can be reflected in more than one direction simultaneously. For example, in some alternative embodiments the light can be reflected in two directions in the same plane (e.g., directions are 180 degrees relative to each other). In another alternative embodiment the light can be directed into different vertical planes (e.g., a first light beam could be emitted between 0-20 degrees from a horizontal plane and the second light beam could be emitted between 40-60 degrees from a horizontal plane). When such a rotating light is mounted to the top of a motor vehicle, the first light beam would direct light just over the top of similarly tall motor vehicles, whereas the second light beam would direct light higher into the sky and be visible from positions farther from the motor vehicle. In alternative embodiments, the orientation of the light beam can be changed during operation (e.g., the light beam can be adjusted to be directed an angle between 0-90 degrees from the horizontal plane). In such embodiments, the reflective surfaces can be configured so that their orientations relative to the reflector body can be changed during operation. For example, the reflective surface can be comprised of a plurality of small mirrors that can be reoriented by electrically controlling micro electrical mechanical switches. 
     The above specification, examples and data provide a complete description of the manufacture and use of the composition of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.