Aircraft LED dome light having rotatably releasable housing mounted within mounting flange

[0001] This invention pertains to general illumination, specifically to providing light from LEDs for use on business jets, commercial aircraft and other transportation vehicles.

[0002] Conventional methods and devices for providing lighting are generally known. For instance, dome lights are installed in business jets and commercial aircraft to allow passengers to see the aisles, door handles and signs. Conventional dome lights utilize arrays of 5 mm LEDs to provide illumination. Problems exist, however, with these conventional lights, because when they are mounted in the ceiling, they do not provide enough ambient light to clearly illuminate the floor and aisle. Instead, in a manner similar to spotlights, only the area directly in front of them is illuminated. This leaves large gaps of dimly lit areas between the lights. Adding more LEDs to a conventional dome light is not desirable because the additional LEDs not only increase the amount of heat generated by the light fixture and increase the size of the light fixture, but also result in light that is too bright for passengers to comfortably look into. A need exists for an improved ambient lighting method and device for the cabins of aircraft and other transportation vehicles. A light fixture is needed that can provide widely dispersed, diffuse, ambient lighting that is not blinding or uncomfortable for passengers to look into.

[0003] The invention is generally directed to a light fixture and method of providing ambient lighting suitable for use in an aircraft cabin. The light fixture utilizes light emitting diodes (LEDs) and a reflector to generate bright but diffuse light. The combination of LEDs and the reflector allows a very small number of LEDs to be used to provide light that is bright enough for a passenger to see relatively large areas clearly, but is diffuse enough that a passenger can comfortably look into the light. The small number of LEDs allows the lighting fixture housing size and weight to be minimized, and decreases the amount of heat produced by the light fixture.

[0013] The invention is generally directed to a light fixture for use in an LED lighting system for an aircraft or other transportation vehicle. Referring to FIGS. 1-3, an embodiment of the light fixture, generally labeled 10, includes a housing 12 having a first end 14 and a second end 16. The housing includes a housing rim 66 adjacent to the first end 14. The housing may have a substantially cylindrical shape as depicted in the embodiment in FIGS. 1-3, however the housing is not limited to a cylindrical shape and in other embodiments of the invention the housing may be another shape. The second end 16 is attached to a base plate 18. The housing 12 defines a passageway between the first end 14 and the second end 16 and has an exterior housing surface 13. A pin 11 extends from the exterior housing surface 13. The embodiment in FIG. 1 may have three pins 11. A different number of pins may be used in other embodiments. The housing 12 may be constructed of any suitable material including, but not limited to, aluminum.

[0014] A reflector 20 is positioned in the passageway within the housing 12. Referring to FIG. 4, the reflector 20 has an illumination end 22 and a bottom end 24. A reflector side wall 26 extends between the illumination end 22 and the bottom end 24 and defines an interior surface 28 (FIG. 2) and an exterior surface 30. At the illumination end 22 there is a reflector rim 32. The reflector side wall 26 is connected to a reflector base 34 that is adjacent to the bottom end 24 of the reflector 20. In an embodiment, the reflector base 34 has a smaller diameter than the reflector rim 32, and the reflector side wall 26 angles upward from the bottom end 24 of the reflector 20 as shown in FIG. 4. The angle may be about fifteen degrees to about seventy-five degrees. The interior surface 28 (FIG. 2) of the reflector side wall 26 is covered with a reflective surface treatment. The reflective surface treatment may be a flat, white, polyurethane paint or any other suitable coating or surface treatment known in the art.

[0015] Referring to FIG. 2, the reflector base 34 is disposed above a printed circuit board (PCB) 40 that is adjacent to the bottom end 24 of the reflector 20. As can be seen in FIG. 6, the PCB 40 has a solder side 42 and a component side 44. Referring again to FIG. 2, the solder side 42 is connected to the top of the base plate 18 by an adhesive layer. The base plate 18 is secured to the housing 12 by screws 15 positioned through the exterior housing surface 13. The base plate 18 has a bottom surface 48. The base plate 18 dissipates heat. In one embodiment, fins 50 extend from the bottom surface 48 of the base plate 18 to aid heat dissipation. There are raised plateaus 52 that extend from the top surface of the base plate 18 and through openings in the PCB 40. In the embodiment shown in FIG. 2, raised circular plateaus 52 extend through openings in the PCB 40 and in the direction of the LED openings 36 (FIG. 5) and the emergency light opening 38 (FIG. 5) in the reflector base 34.

[0016] The lighting device utilizes LEDs to provide illumination. One embodiment of the invention may utilize three, white, high-output, side-emitting LEDs for illumination. The invention is not limited to white, side-emitting LEDs; other types or colors of LEDs may be used. In the embodiment, illustrated in FIG. 3, three white, high-output, side-emitting LEDs 54 are used for illumination, and an additional emergency LED 56 is used for lighting under emergency conditions. The emergency LED 56, in the embodiment illustrated in FIG. 3, is a white, Lambertian LED. The emergency LED 56 is not limited to a white, Lambertian LED; in other embodiments a different type or color of LED may be used. In the embodiment depicted in FIGS. 2-3, the emergency LED 56 is positioned in the center of the reflector 20. The position of the emergency LED 56 is not limited to the center of the reflection 20.

[0017] The reflector base 34 defines openings for the LEDs to be mounted through. In an embodiment seen in FIG. 5, there are three LED openings 36 in the reflector base 34. Each LED opening 36 is large enough to allow a LED to protrude through it. In the embodiment, there is also one emergency light opening 38 in the reflector base 34. Likewise, the emergency light opening 38 is large enough to allow protrusion through of an emergency LED 56. In still another embodiment the reflector base 34 may only include a LED opening 36.

[0018] Referring now to FIG. 2, the LEDs 54, 56 are attached to the raised plateaus 52 of the base plate 18 using an adhesive layer, and extend through the LED openings 36 (FIG. 5) and through the emergency light opening 38 (FIG. 5) in the reflector base 34. In the current embodiment, the base plate 18 and the raised plateaus 52, function as a heat sink drawing heat away from the LEDs 54, 56 and dissipating it through the fins 50 and the bottom surface 48 of the base plate 18. This creates a short, efficient thermal path to the heat dissipating surfaces, thereby minimizing the lighting device size and profile and reducing overall weight. In one embodiment, the base plate 18 is made of an aluminum alloy.

[0019] Referring to FIG. 2, the lighting fixture has a first lens 60, a filter 64, and a second diffusing lens 62 all attached to the first end 14 of the housing 12 and held in place by the housing rim 66. In one embodiment, both the first lens 60 and the diffusing lens 62 are made of polycarbonate and the filter 64 is a colored polycarbonate filter. It is not necessary, however, to use a filter to achieve effective diffuse, ambient lighting.

[0020] The operation of the embodiment of the lighting device 10 in FIGS. 1-6 will now be discussed. When in operation, power is supplied to the lighting device 10 such that the three white side-emitting LEDs 54 are illuminated and emit light from their respective sides. The light emitted by the side-emitting LEDs 54 (FIG. 2) is mixed by the interior surface 28 of the reflector side wall 26 and projected forward by the angle of the side walls 26, thereby approximating a parabolic reflector. The beam of light produced is projected through the diffusing lens 62, the filter 64, and the first lens 60. In this particular embodiment a warm filter 64 is used to provide warm toned light. It is possible, however, to provide bright ambient light without the filter 64 or with a filter designed to provide the desired lighting effect. The diffusing lens 62, and first lens 60 disperse the beam of light reflected by the reflector 20 into widely distributed light.

[0021] For exemplary purposes, if the lighting device, as described above, is mounted into the overhead of the passenger aisle of a commercial aircraft, the light provided will be bright enough that a passenger can clearly see the floor, aisle, and the surrounding space but not so concentrated that the light is blinding when viewed directly.

[0022] In the embodiment illustrated in FIGS. 1-6, the three side-emitting LEDs 54 are used to provide ambient light during non-emergency conditions and the one emergency LED 56 is used to provide light only during emergency conditions. In this embodiment, only the emergency LED 56 will be illuminated during the emergency conditions; the side-emitting LEDs 54 will not be illuminated under emergency conditions. In another embodiment of the lighting device 10, only the three side-emitting LEDs 54 are used to provide ambient light.

[0023] The lighting device 10 (72 in FIG. 7) has been designed so that it can be mounted without hardware from the interior side of an aircraft 100 ceiling panel 101 (see FIGS. 3 and 7) or wall panel 102 see FIG. 7 into a previously installed mounting flange assembly. Thus, replacement of the lighting device only requires access to the interior side of the ceiling or wall panel. Only during the initial installation of the lighting device 10 is access possibly required to the back of the panels in which the lights are installed. This is important since dome lights are often mounted in aircraft ceiling and walls panels making the lights difficult to access from the back. FIG. 2 shows an embodiment of a mounting flange assembly holding the lighting fixture. In FIG. 2, the mounting flange assembly comprises a mounting flange 68 and a threaded securing nut 69, which may be constructed of aluminum alloy. The lighting device is received into the mounting flange 68 with the housing rim 66 disposed on top of the mounting flange 68.

[0024] FIG. 8 is an illustration of an embodiment of the mounting flange 68. The mounting flange 68 has a rim 81 and a bottom flange edge 82. The mounting flange 68 defines at least one flange opening 83. In the embodiment illustrated in FIG. 8, there may be three flange openings 83, although other numbers of flange openings are possible. The flange opening 83 in the embodiment in FIG. 8 comprises a first channel 84 adjacent to a second channel 85. The first channel 84 is substantially perpendicular to the rim 81 and the second channel 85 is substantially horizontal to the rim 81. The second channel 85 has an endpoint 87. The lighting device 10 (FIG. 1) is inserted into the mounting flange 68 such that a pin 11 (FIG. 1) disposed on the housing 12 slides into the first channel 84 (FIG. 8). The lighting device 10 (FIG. 1) is manipulated such that the pin 11 (FIG. 1) is moved adjacent to the endpoint 87 (FIG. 8) of the second channel 85 (FIG. 8). A resilient member 67 (FIG. 2), such as a wave washer, is disposed between the rim 81 of the mounting flange 68 and the housing rim 66. The resilient member 67 causes a force to be applied to the pin 11 (FIG. 1) positioned in the second channel 85 (FIG. 8). The force applied by the resilient member 67 causes the pin 11 to be held in place and holds the lighting device to the mounting flange. In the embodiment shown in FIG. 8 there are three flange openings 83 into which each receives a pin 11.

[0025] The manner in which the lighting device 10 is electrically connected will now be described. For the embodiment illustrated in FIGS. 1-6, the side-emitting LEDs 54 are each electrically connected to drive circuitry located on the PCB 40. The side-emitting LEDs 54 are connected in series. The series of side-emitting LEDs 54 are connected to a 28 volt DC source 78 (the power source is shown in FIG. 7) by way of a switching regulator 45 and controlled by a programmable microcontroller 43 as shown in FIG. 6.

[0026] The microcontroller 43 runs firmware that allows the use of a range of control signals known in the art such as momentary switches, Hall-Effect sensors, and pulse controls. In one embodiment, a pulse controlled signal is used to control the intensity of the side-emitting LEDs 54.

[0027] The emergency LED 56 receives current from a power source 79 (as shown in FIG. 7) different from that of the side-emitting LEDs 54. The side-emitting LEDs 54 are not illuminated at the same time as the emergency LED 56.

[0028] An example of a lighting system in which the invention may be used is shown in FIG 7. The lighting system, generally labeled 70, includes multiple light fixtures 72. Each light fixture is electrically connected to the system at a specific location along a wiring harness 73. The system 70 also includes lighting controller 76. The lighting controller 76 transmits a control signal to each of the light fixtures 72 to provide illumination for the aisles of an aircraft 100.

[0029] All references, including publications, patent applications and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and set forth in its entirety herein.

[0030] The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples or exemplary language (e.g., “such as”) provided herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0031] Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. It should be understood that the illustrated embodiments are exemplary only, and should not be taken as limiting the scope of the invention.