Abstract:
The present disclosure relates to a lighting module wherein a DC-DC converter and an LED module are provided as an integral part of the lighting module, and an AC-DC module is provided separately from the lighting module. The AC-DC module is effectively a remote power supply that can be easily replaced without having to replace, reconfigure, or otherwise modify the lighting module. With this configuration, the DC-DC module may be tuned for the particular LED module of the lighting module, and in the case of a failure of the AC-DC module, the AC-DC module can be replaced without having to replace or retune the DC-DC module.

Description:
This application claims the benefit of U.S. provisional patent application No. 61/470,771 filed Apr. 1, 2011, the disclosure of which is incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE DISCLOSURE 
     The present disclosure relates to lighting modules. 
     BACKGROUND 
     In recent years, a movement has gained traction to replace incandescent light bulbs with lighting fixtures that employ more efficient lighting technologies. One such technology that shows tremendous promise employs light emitting diodes (LEDs). Compared with incandescent bulbs, LED-based light fixtures are much more efficient at converting electrical energy into light and are longer lasting, and as a result, lighting fixtures that employ LED technologies are expected to replace incandescent bulbs in residential, commercial, and industrial applications. 
     As such, there is need for LED based lighting fixtures that are capable of being employed in an efficient and economical manner in residential, commercial, and industrial applications. 
     SUMMARY 
     The present disclosure relates to a lighting module wherein a DC-DC converter and an LED module are provided as an integral part of the lighting module, and an AC-DC module is provided separately from the lighting module. The AC-DC module is effectively a remote power supply that can be easily replaced without having to replace, reconfigure, or otherwise modify the lighting module. With this configuration, the DC-DC module may be tuned for the particular LED module of the lighting module, and in the case of a failure of the AC-DC module, the AC-DC module can be replaced without having to replace or retune the DC-DC module. 
     In one embodiment, a lighting module is mounted within a mounting housing and receives DC power from a remote AC-DC module that is mounted outside of the mounting housing. The lighting module includes an LED module comprising a plurality of LEDs and a DC-DC module. The DC-DC module is configured to receive a DC power signal from the remote AC-DC module and provide at least one drive signal to drive the plurality of LEDs of the LED module. 
     In this embodiment, the lighting module may be configured to receive from the remote AC-DC module an output dimming signal based on a desired level of dimming for the plurality of LEDs, wherein the DC-DC module is configured to control the at least one drive signal based on the output dimming signal. The LED module is configured to provide a feedback signal to the DC-DC module, which is further configured to control the at least one drive signal based at least in part on the feedback signal. For example, the LED module is configured to detect a fault or temperature associated with the LED module and the feedback signal relates to the fault or temperature associated with the LED module. 
     In another embodiment, the DC-DC module is configured to provide a feedback signal to the remote AC-DC module, which is further configured to control the DC power supply based at least in part on the feedback signal. The DC-DC module is configured to detect a fault or temperature associated with the DC-DC module and the feedback signal relates to the fault or the temperature associated with the DC-DC module. 
     In another embodiment, the remote AC-DC module is configured to generate and provide to the DC-DC module an output dimming signal based at least in part on the feedback signal, and the DC-DC module is configured to control the at least one drive signal based on the output dimming signal. The remote AC-DC module may be configured to generate the output dimming signal based on an input dimming signal that is separate from the AC power signal. Alternately, the remote AC-DC module may be configured to generate the output dimming signal based on a characteristic of the AC power signal. 
     In yet another embodiment, a lighting assembly is provided that includes a lighting module and an AC-DC module that is located remotely from the lighting module. The lighting module includes an LED module having a plurality of LEDs and a DC-DC module. The DC-DC module may be configured to receive a DC power signal and to provide at least one drive signal to drive the plurality of LEDs of the LED module. The AC-DC module may be configured to convert an AC power signal to the DC power signal for the DC-DC module. The lighting module is configured to be mounted inside of a mounting housing and the AC-DC module is configured to be mounted outside of the mounting housing. The resultant lighting assembly may include a mounting frame, wherein the mounting housing is mounted to the mounting frame and the lighting assembly forms a recessed lighting fixture for ceilings. The lighting assembly may further include a junction box mounted on the mounting frame and outside of the mounting housing, wherein the AC-DC module is mounted inside the junction box and the lighting module is mounted inside the mounting housing. 
     Those skilled in the art will appreciate the scope of the disclosure and realize additional aspects thereof after reading the following detailed description in association with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings incorporated in and forming a part of this specification illustrate several aspects of the disclosure, and together with the description serve to explain the principles of the disclosure. 
         FIG. 1  is a block diagram of electronics employed for a lighting fixture according to one embodiment of the disclosure. 
         FIG. 2  illustrates a mounting assembly in which the lighting fixture of  FIG. 1  is provided. 
         FIGS. 3A through 3G  are various views of a lighting module for the lighting fixture of  FIG. 1  according to one embodiment of the disclosure. 
         FIGS. 4A through 4G  are various views of a lighting module for the lighting fixture of  FIG. 1  according to one embodiment of the disclosure. 
         FIGS. 5A and 5B  are isometric views of the heat sinks for the embodiments illustrated in  FIGS. 3A through 3G  and  FIGS. 4A through 4G , respectively. 
         FIGS. 6A and 6B  are isometric views of the housings for the embodiments illustrated in  FIGS. 3A through 3G  and  FIGS. 4A through 4G , respectively. 
     
    
    
     DETAILED DESCRIPTION 
     The embodiments set forth below represent the necessary information to enable those skilled in the art to practice the disclosure and illustrate the best mode of practicing the disclosure. Upon reading the following description in light of the accompanying drawings, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure. 
     It will be understood that relative terms such as “front,” “forward,” “rear,” “below,” “above,” “upper,” “lower,” “horizontal,” or “vertical” may be used herein to describe a relationship of one element, layer or region to another element, layer or region as illustrated in the figures. It will be understood that these terms are intended to encompass different orientations of the device in addition to the orientation depicted in the figures. 
     With reference to  FIG. 1 , the electronics for one embodiment of the disclosed lighting fixture are illustrated. As shown, the electronics include an AC-DC (alternating current-direct current) module  10 , a DC-DC (direct current-direct current) module  12 , and an LED (light emitting diode) module  14 . The DC-DC module  12  and the LED module  14  cooperate to form a light engine  16 , wherein the DC-DC module  12  generates the requisite drive currents I N  to drive corresponding strands of LEDs provided by the LED module  14 . The DC-DC module  12  is powered and controlled in part by the AC-DC module  10 . 
     The AC-DC module  10  is configured to receive an AC power supply signal P AC  and a input dimming signal S DIM , and based on these signals, provide a DC power supply signal P DC  and an output dimming signal S D  to the DC-DC module  12 . The AC-DC module  10  includes circuitry to step down and rectify the AC power supply signal P AC  to a desired DC voltage, which represents the DC power supply signal P DC . The DC power supply signal P DC  is used to power the DC-DC module  12 . 
     The input dimming signal S DIM  is an analog or digital control signal that represents a desired level of dimming relative to a maximum desirable lumen output of an LED module  14 . The input dimming signal S DIM  may be provided from an appropriate remote control module or lighting switch (not shown), as will be appreciated by those skilled in the art. The AC-DC module  10  provides the necessary circuitry to process the input dimming signal S DIM  and generate a corresponding output dimming signal S D  based on the desired level of dimming. As will be appreciated by one skilled in the art, the output dimming signal S D  is generally a pulse width modulated (PWM) signal wherein the duty cycle of the output dimming signal S D  is effectively a function of the input dimming signal S DIM . Since the input dimming signal S DIM  corresponds to a desired level of dimming, the duty cycle of the output dimming signal S D  is a function of the desired level of dimming. 
     In an alternative embodiment, the AC power supply signal P AC  may be provided with the use of a dimmer for lighting control. The dimmer may be leading or trailing edge controlled. The portion of the AC waveform received in the AC power supply signal P AC  corresponds to the desired level of dimming. As such, the AC-DC module  10  is configured to analyze the AC power supply signal P AC  and generate the output signal S D  based thereon. 
     The DC-DC module  12  includes a DC-DC converter and multiple current sources that are supplied by the DC-DC converter. The current sources generate the individual drive currents I N , which are illustrated as I 1 , I 2 , and I 3 , and are used to respectively drive three different strands of LEDs of the LED module  14 . The DC-DC converter of the DC-DC module  12  is configured to drive the current sources to control the drive currents I 1 , I 2 , and I 3  such that the respective strands of LEDs output light at a desired color as well as a desired intensity based on the output dimming signal S D . In one embodiment, one or more strands may be formed from red LEDs, while one or more of the other strands may be formed from blue-shifted yellow LEDs. The different strands are driven by the drive currents I 1 , I 2 , and I 3  such that the light emitted from the strands mixes to form light at a desired color temperature as well as at a desired intensity based on the desired level of dimming. 
     The DC-DC module  12  may be configured to provide one or more feedback signals F DC  to the AC-DC module  10 . The feedback signals F DC  may provide temperature, fault, or other information bearing on the operation of the DC-DC module  12 , and the AC-DC module  10  may be configured to respond to the feedback signals F DC  and adjust or control the output dimming signal S D , the DC power supply signal P DC , or both, in a desired manner. Similarly, the LED module  14  may be configured to provide one or more feedback signals F LED  to the DC-DC module  12 . The feedback signals F LED  may provide temperature, fault, or other information bearing on the operation of the LED module  14 , and the DC-DC module  12  may be configured to respond to the feedback signals F LED  and adjust or control the drive currents I N  in a desired manner. 
     For the present disclosure, the DC-DC module  12  and the LED module  14  of the light engine  16  are provided in a lighting module  18 , while the AC-DC module  10  is designed to be mounted apart from the lighting module  18 , as shown in  FIG. 2 . As illustrated, the lighting module  18  is mounted inside of a mounting housing  20 , while the AC-DC module  10  is mounted outside of the mounting housing  20 . In particular, the AC-DC module  10  is mounted to or inside a junction box  22 . The mounting housing  20  and the junction box  22  may be coupled together via a mounting frame  24  to form a mounting assembly  26 . For example, the mounting frame  24  of the mounting assembly  26  may be configured as a recessed lighting assembly, which mounts between adjacent ceiling joists such that the mounting housing  20  is suspended at a location where the lighting module  18  is desired. A cable  28  is used to connect the AC-DC module  10  and the DC-DC module  12 . The cable  28  is shown running from the AC-DC module  10  to the lighting module  18  through an upper portion of the mounting housing  20 . The cable  28  may be provided in a conduit in select embodiments. 
     The DC-DC module  12  and the LED module  14  are mounted to or in portions of the lighting module  18 . In addition to the DC-DC module  12  and the LED module  14 , the lighting module  18  comprises a heat sink  30 , a support bracket  32 , a mixing chamber  34  having a reflective interior, a diffuser  36 , and a lens  38 . In the illustrated embodiment, the heat sink  30  provides for a compartment  40  in which the DC-DC module  12  is mounted. As such, the DC-DC module  12  is mounted within the confines of the outer boundaries of the heat sink  30 . 
     In this embodiment, the LED module  14  is mounted to the heat sink  30  wherein a thermal pad (not shown) may be used to thermally couple the LED module  14  to the heat sink  30 . The thermal pad may be formed from any thermally conductive material, such as metal or thermally conductive resins. Bolts or other fastening mechanisms may be used to attach the LED module  14  and the thermal pad to a forward surface of the heat sink  30 . Notably, the LED module  14  is illustrated as a printed circuit board (PCB) having the LEDs of the different strands of LEDs arranged in an array. A cable assembly is used to connect the LED module  14  to the DC-DC module  12 . 
     The support bracket  32  is a primary structural component for the lighting module  18 . The support bracket  32  has a bottom rim, which forms a rear opening and mounts to the heat sink  30  with bolts, such that at least the array of LEDs of the LED module  14  are exposed though the rear opening. In the illustrated embodiment, the rear opening of the support bracket  32  is sized and shaped to correspond to and receive the PCB of the LED module  14 . The support bracket  32  also has a forward opening, which receives the mixing chamber  34 . The mixing chamber  34  may take various forms. In the illustrated embodiment, the mixing chamber  34  has a conical or parabolic body with a rear opening that is sized and shaped such that the array of LEDs of the LED module  14  remains exposed. The mixing chamber  34  also has a forward opening formed by a forward flange. The mixing chamber  34  concentrically resides inside the support bracket  32  wherein the rear surface of the forward flange of the mixing chamber  34  rests on the forward surface of the support bracket&#39;s forward flange. 
     A planar diffuser  36 , which generally corresponds in shape and size to the outside periphery of the forward flange of the mixing chamber  34 , may be placed on the forward surface of the forward flange of the mixing chamber  34 , and thus cover the forward opening of the mixing chamber  34 . The degree and type of diffusion provided by the diffuser  36  may vary from one embodiment to another. Further, color, translucency, or opaqueness of the diffuser  36  may vary from one embodiment to another. Diffusers  36  are typically formed from a polymer or glass, but other materials are viable. Similarly, a planar lens  38 , which generally corresponds to the shape and size of the diffuser  36  as well as the outside periphery of the forward flange of the mixing chamber  34 , may be placed over the diffuser  36 . As with the diffuser  36 , the material, color, translucency, or opaqueness of the lens  38  may vary from one embodiment to another. Further, both the diffuser  36  and the lens  38  may be formed from one or more materials or one or more layers of the same or different materials. While only one diffuser  36  and one lens  38  are depicted, the lighting module  18  may have multiple diffusers  36  or lenses  38 ; no diffuser  36 , no lens  38 , no diffuser  36  or lens  38 , or an integrated diffuser and lens (not shown) in place of the illustrated diffuser  36  and lens  38 . 
     A retention ring may be provided to hold the mixing chamber  34 , diffuser  36 , and lens  38  in place. In operation, light emitted from the array of LEDs of the LED module  14  is mixed inside the mixing chamber  34  and directed out through the lens  38  in a forward direction to form a light beam. As noted, the array of LEDs of the LED module  14  may include LEDs that emit different colors of light. For example, the array of LEDs may include both red LEDs that emit red light and blue-shifted yellow or green LEDs that emit bluish-yellow or bluish green light, wherein the red and bluish-yellow or bluish-green light is mixed to form “white” light at a desired color temperature. For a uniformly colored light beam, relatively thorough mixing of the light emitted from the array of LEDs is desired. Both the mixing chamber  34  and the diffuser  36  play a role in mixing the light emanated from the array of LEDs of the LED module  14 . 
     Certain light rays, which are referred to as non-reflected light rays, emanate from the array of LEDs of the LED module  14  and exit the mixing chamber  34  through the diffuser  36  and lens  38  without being reflected off of the interior surface of the mixing chamber  34 . Other light rays, which are referred to as reflected light rays, emanate from the array of LEDs of the LED module  14  and are reflected off of the reflective interior surface of the mixing chamber  34  one or more times before exiting the mixing chamber  34  through the diffuser  36  and lens  38 . With these reflections, the reflected light rays are effectively mixed with each other and at least some of the non-reflected light rays within the mixing chamber  34  before exiting the mixing chamber  34  through the diffuser  36  and the lens  38 . The diffuser  36  functions to diffuse, and as result mix, the non-reflected and reflected light rays as they exit the mixing chamber  34 , wherein the mixing chamber  34  and the diffuser  36  provide sufficient mixing of the light emanated from the array of LEDs of the LED module  14  to provide a light beam of a consistent color. In addition to mixing light rays, the diffuser  36  is designed and the mixing chamber  34  shaped in a manner to control the relative concentration and shape of the resulting light beam that is projected from the diffuser  36  and the lens  38 . For example, a first lighting module  18  may be designed to provide a concentrated beam for a spotlight, wherein another may be designed to provide a widely dispersed beam for a floodlight. Notably, finishing trim (not shown) may also be provided to further contribute to light mixing, beam shaping, or both. The interior surface of the finishing trim may range from a highly reflective metal coating to a matte black finish, depending on the desired aesthetics and functionality. 
       FIGS. 3A through 3G  and  FIGS. 4A through 4G  respectively illustrate various views of two embodiments of the disclosure. In these embodiments and as described in further detail below, the side(s) of the heat sink  30  may be formed to have recessed portions  30 R that extend from the forward surface of the heat sink  30  to the rear surface of the heat sink  30 . A compartment  40  may be provided in and along one of the recessed portions  30 R of the heat sink  30 , such that the compartment  40  does not extend past the overall lateral dimensions of the heat sink  30 . As clearly depicted in  FIGS. 3F and 3G , the compartment  40  may be provided by a separate housing that mounts to the heat sink  30  and resides substantially or entirely within a recessed portion  30 R. The housing may optionally have a bottom and a detachable lid, such that the DC-DC module  12  is protected from the elements.  FIGS. 3F ,  3 G, and  4 E illustrate the lid being in place on the compartment  40 .  FIGS. 3F and 4E  illustrate the DC-DC module  12  being located inside of the compartment  40  through a cut-away provided in the lid of the compartment  40 . Alternatively, the main body of the compartment  40  may be formed as an integral part of the heat sink  30  and be configured to receive the optional lid. 
     As illustrated in  FIGS. 4A through 4G , the cable  28 , as well as any conduit in which the cable  28  is run, may also be configured to exit the support bracket  32  adjacent a recessed portion  30 R of the heat sink  30 . As such, the cable  28  may run through the recessed portion  30 R and within the outer periphery of the heat sink  30 . 
     In select embodiments, the support bracket  32  is configured to form an air gap between the fins of the heat sink  30  and the main body of the support bracket  32  to provide for additional airflow through the fins of the heat sink  30 . 
       FIGS. 5A and 5B  illustrate the heat sinks  30  and the respective recessed portions  30 R for the respective embodiments. The heat sinks  30  include radial fins  44  that are substantially parallel to a central axis of the substantially cylindrical heat sink  30 . In the illustrated embodiments, shorter fin sections have a group of adjacent radial fins  44 , which radially extend to a first distance relative to the central axis of the heat sink  30 . The shorter fin sections that correspond to the recessed portion  30 R are provided among or between one or more longer fin sections. As illustrated, the embodiment of  FIG. 5A  has two shorter fin sections, and thus, two recessed portions  30 R. The embodiment of  FIG. 5B  has one shorter fin section, and thus one recessed portion  30 R. The number of shorter and longer fins sections may vary from one embodiment to the next. 
     The longer fin sections have a group of adjacent radial fins, which radially extend to a second distance relative to the central axis of the heat sink  30 , wherein the second distance is greater than the first distance. Relative to the longer fin sections, the shorter fin sections effectively form the recessed portions  30 R. While only longer and shorter fin sections are illustrated, one or more intermediate fin sections (not illustrated) may be provided wherein the intermediate fin sections (not shown) have a group of adjacent radial fins, which radially extend to a third distance relative to the central axis of the heat sink  30 , wherein the third distance is between the first and second distances. 
     As noted above, the recessed portions  30 R of the heat sink  30  provide channels in which the compartment  40  for the DC-DC module  12  may be formed or mounted. The recessed portions  30 R may also act as cable chases. 
     As illustrated in  FIGS. 5A and 5B , the heat sink  30  may include a solid, generally cylindrical core  46 , wherein the center axis of the heat sink  30  generally corresponds to the center axis of the core  46 . The radial fins  44  effectively extend outward from the outer surface of the cylindrical core  46 , wherein the cylindrical core  46  and the radial fins  44  form the heat sink  30 . In alternate embodiments, the core  46  may be hollow or have one or more openings or cavities therein. Threaded mounting holes may be formed on the forward and rear surfaces or the fins of the heat sink  30  to facilitate attaching elements, such as the support bracket  32 , LED module  14 , the compartment  40 , and the like. In one embodiment, the entirety of the heat sink  30  is extruded as a single integrated component from highly thermally conductive metal, such as aluminum, copper, gold, or the like. As noted, the compartment  40  that may be used to house the DC-DC module  12  may by integrally formed with the heat sink  30  or may be formed in a separate housing that is mounted to the heat sink  30 , and perhaps in a recessed portion  30 R provided therein. 
       FIGS. 6A and 6B  illustrate exemplary support brackets  32  for the respective embodiments. 
     Those skilled in the art will recognize improvements and modifications to the embodiments of the present disclosure. For example, although the above embodiments are directed to a lighting module  18  and a remote AC-DC module  10  wherein the primary components of the lighting module  18  are substantially cylindrical in nature; however, any one or all of these components may take on other forms, such as rectangular, triangular, elliptical, and the like. As another example, the DC-DC module  12  may be integrated with the LED module  14 . All such improvements and modifications are considered within the scope of the concepts disclosed herein.